bio final

F1. Explain how the term 'species' can vary between groups of organisms. Compare and contrast the four main species concepts, addressing their uses and limitations. Given a scenario, determine which species concept would be most appropriate to determine if two organisms were the same species. [Comprehension, Analysis, Application]

Species are a group of organisms because different species may have different criteria for determining whether they are from the same species or just two different species that may have similar characteristics. Generally, a species is a group of organisms that can interbreed and produce fertile offspring, but there are certain exceptions.

FOUR SPECIES CONCEPTS
Biological Species concept
This concept is used by taxonomists
Those species that can interbreed and produce viable offspring
Can be used to define diploid, sexually reproducing organisms
It relies on reproductive isolation - when 2 populations cannot interbreed, they are not from the same species
States that no gene flow occurs between two populations if reproductive isolation occurs because they cannot reproduce together
It uses multiple lines of evidence.
There are two types of reproductive isolation
Pre zygotic
Temporal
Habitat
Behavioral
Gametic behavior
Mechanical
Post zygotic
Hybrid viability
Hybrid sterility
Disadvantages
Can't be found in fossils
Difficult to apply - geographic barriers
Determining the boundaries of a species can be difficult, as genetic and morphological data can vary within and between populations.
Lack of consensus: There is often a lack of consensus among researchers on the appropriate criteria for defining a species, which can lead to inconsistencies in species designations.
Can be subjective: The interpretation of genetic and morphological data can be subjective, leading to different conclusions about species boundaries.
May not reflect ecological or functional differences: The phylogenetic species concept does not necessarily reflect ecological or functional differences between groups of organisms, which can be important in some contexts.

2. Morphospecies Concept
The morphological species concept defines a species based on physical characteristics such as anatomical features, size, shape, coloration, and other observable traits
Morphological differences between individuals of the same/different species
Fossil identification
Helpful with extinct/extant species
Can be applied to extinct AND living organisms
Helpful when genetic data is unavailable
Disadvantages
Cannot identify cryptic species
Limit of variation between populations - characteristics can vary within populations, making it difficult to determine if individuals belong to the same or different species.
the physical features used to distinguish between species can also overlap, leading to ambiguity in species identification.
May not reflect genetic differences

3. Ecological species concept
Organisms that have the same resources, environmental tolerances and face the same predators
Identifies species based on their role in the environment
Ecological niche, behaviour, and interactions with other species
Can be used to identify bacterial, archaea, or organisms that reproduce asexually
Reflects ecological interactions
Useful for conservation research and efforts
Can reveal cryptic species
Disadvantages
Not useful if one does now know anything about the role of the organism
Difficult to apply - ecological interactions can be hard be complex
Ecological differences may not reflect genetic differences and differences species can occupy similar ecological niches
Limited to organisms - cant apply to bacteria and viruses as they do not have well defined ecological niches
May not reflect historical relationships

4. Phylogenetic species concept
Evolutionary history of populations based on the
DARWIN - stated that all species are related by common ancestry
All species form a MONOPHYLETIC group, or clade
They are identified by synapomorphies at genetic, mental or structural levels
According to this concept, species are a group of organisms that are bound by ancestors based on their morphological and genetic traits and lineage
Widely applicable
Reflects evolutionary history
Can be applied to all organisms
Disadvantages
Can be difficult to apply - incomplete data on lineages, etc
Limited data
May not reflect functional differences

Biological Species concept

This concept is used by taxonomists
Those species that can interbreed and produce viable offspring
Can be used to define diploid, sexually reproducing organisms
It relies on reproductive isolation - when 2 populations cannot interbreed, they are not from the same species
States that no gene flow occurs between two populations if reproductive isolation occurs because they cannot reproduce together
It uses multiple lines of evidence.

There are two types of reproductive isolation

Pre zygotic
Temporal
Habitat
Behavioral
Gametic behavior
Mechanical

Post zygotic
Hybrid viability
Hybrid sterility

Disadvantages of Biological Species concept

Can't be found in fossils
Difficult to apply - geographic barriers
Determining the boundaries of a species can be difficult, as genetic and morphological data can vary within and between populations.
Lack of consensus: There is often a lack of consensus among researchers on the appropriate criteria for defining a species, which can lead to inconsistencies in species designations.
Can be subjective: The interpretation of genetic and morphological data can be subjective, leading to different conclusions about species boundaries.
May not reflect ecological or functional differences: The phylogenetic species concept does not necessarily reflect ecological or functional differences between groups of organisms, which can be important in some contexts.

Morphospecies Concept

The morphological species concept defines a species based on physical characteristics such as anatomical features, size, shape, coloration, and other observable traits
Morphological differences between individuals of the same/different species
Fossil identification
Helpful with extinct/extant species
Can be applied to extinct AND living organisms
Helpful when genetic data is unavailable

Disadvantages of morphospecies concept

Cannot identify cryptic species
Limit of variation between populations - characteristics can vary within populations, making it difficult to determine if individuals belong to the same or different species.
the physical features used to distinguish between species can also overlap, leading to ambiguity in species identification.
May not reflect genetic differences

Ecological species concept

Organisms that have the same resources, environmental tolerances and face the same predators
Identifies species based on their role in the environment
Ecological niche, behaviour, and interactions with other species
Can be used to identify bacterial, archaea, or organisms that reproduce asexually
Reflects ecological interactions
Useful for conservation research and efforts
Can reveal cryptic species

disadvantages of ecological species concept

Not useful if one does now know anything about the role of the organism
Difficult to apply - ecological interactions can be hard be complex
Ecological differences may not reflect genetic differences and differences species can occupy similar ecological niches
Limited to organisms - cant apply to bacteria and viruses as they do not have well defined ecological niches
May not reflect historical relationships

Phylogenetic species concept

Evolutionary history of populations based on the
DARWIN - stated that all species are related by common ancestry
All species form a MONOPHYLETIC group, or clade
They are identified by synapomorphies at genetic, mental or structural levels
According to this concept, species are a group of organisms that are bound by ancestors based on their morphological and genetic traits and lineage
Widely applicable
Reflects evolutionary history
Can be applied to all organisms

Disadvantages of phylogenetic species concept

Can be difficult to apply - incomplete data on lineages, etc
Limited data
May not reflect functional differences

Explain the concept of subspecies, and how it can pose a challenge to the Biological Species Concept. Define a cline and explain how a species could vary over its geographic range, relating this concept to natural selection. [Comprehension]

In the morphospecies concept, subspecies have unique features but are not different enough to consider a new separate species. They are populations within a species that are geographically separated from each other and have some distinct morphological, behavioral, or genetic traits that set them apart from other populations within the species. Subspecies can arise due to factors such as isolation, adaptation to different environments, or genetic drift.
The Biological Species Concept defines a species as a group of organisms that can interbreed and produce viable offspring. However, subspecies can sometimes interbreed with each other, producing viable offspring, but not with other populations of the same species that are further apart on the evolutionary scale. This can pose a challenge to the Biological Species Concept, as it blurs the line between what is considered a distinct species and what is not.
A cline refers to the gradual variation in a particular trait or set of traits across the geographic range of a species. For example, a species of bird may have different colored feathers, with individuals in the northern part of its range having darker feathers than those in the southern part. Clines can be the result of natural selection acting on the populations in different environments, with certain traits being favored in one area over another.
Natural selection can drive the evolution of subspecies and clines. Populations that are isolated from each other may evolve in different ways due to different selection pressures, leading to the development of distinct subspecies. Similarly, natural selection can act on a species' traits as they vary across its geographic range, leading to the development of clines. The variation in traits within a species can provide the raw material for natural selection to act upon, leading to adaptations to local environments and the emergence of new subspecies or the evolution of a cline.

Explain the concept of subspecies

subspecies have unique features but are not different enough to consider a new separate species. They are populations within a species that are geographically separated from each other and have some distinct morphological, behavioral, or genetic traits that set them apart from other populations within the species. Subspecies can arise due to factors such as isolation, adaptation to different environments, or genetic drift.

Describe and recognize examples of prezygotic and postzygotic isolating mechanisms. Identify prezygotic mechanisms that inhibit mating attempts, and those that limit fertilization, but not mating attempts. [Comprehension, Analysis]

Prezygotic isolation (before the zygote forms) is isolation which prevents individuals from different species from mating successfully. There are different types of prezygotic isolation, such as: temporal, habitat, behavioural, gametic barrier, and mechanical. Some of these prevent mating from even occurring and some prevent fertilization after mating has occurred. Mechanisms that inhibit mating attempts: temporal, habitat, behavioural. Mechanisms that limit fertilization: gametic barrier and mechanical.
Postzygotic isolation: after the zygote has formed, isolation in which the hybrid offspring of matings between members of different species either don't survive or cannot reproduce. There are two types: hybrid viability and hybrid sterility.

Compare two geographic modes of speciation (allopatric and sympatric), identifying situations that could lead to each, and referring to microevolutionary processes; identify examples of each type of speciation. [Knowledge, Comprehension, Analysis]

Allopatric -
occurs when populations of a species are geographically isolated from each other and diverge over time due to different selective pressures or genetic drift.
This can occur due to natural barriers like mountains, oceans, or rivers that physically separate populations, or due to human-caused changes to the landscape like habitat fragmentation or introduction of non-native species.
In allopatric speciation, reproductive isolation can gradually develop between the separated populations due to genetic changes that occur in each group over time. If the populations are reunited, they may no longer be able to interbreed successfully, even if they are brought back into contact.
Allopatric speciation is often driven by microevolutionary processes such as mutation, genetic drift, and natural selection acting on the separated populations.
Example
emergence of Darwin's finches in the Galapagos Islands.
The finches are believed to have originated from a single ancestral population that arrived on the islands millions of years ago.
Over time, the finches became isolated from each other due to geographic barriers such as mountains, leading to the development of distinct subspecies with different beak sizes and shapes that were adapted to their specific ecological niches.
Sympatric -
occurs when new species emerge within the same geographic area without any physical barriers separating the populations.
This can occur due to a variety of mechanisms, such as disruptive selection, polyploidy, or ecological differentiation
In disruptive selection, divergent selection pressures favor different traits within a population, leading to the emergence of two or more subpopulations with distinct traits.
In polyploidy, a rare event in which an organism gains an extra set of chromosomes, can create a reproductive barrier between the polyploid individual and its parental population, leading to the emergence of a new species.
Ecological differentiation can occur when populations exploit different resources or niches within the same geographic area, leading to reproductive isolation over time.
An example of sympatric speciation is the emergence of the apple maggot fly in North America. The fly originally fed on hawthorn berries, but after the introduction of apples, some populations began to specialize on this new resource. Over time, reproductive isolation between the hawthorn-feeding and apple-feeding populations developed, leading to the emergence of two distinct species.

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

sympatric speciation

The formation of new species in populations that live in the same geographic area

Explain the significance of polyploidy, chromosomal alterations (e.g., rearrangements, duplications), and hybridization in speciation. [Comprehension

Chromosome alterations are chromosomal mutations that involve the mutation of a long segment of DNA. Sometimes this alteration could lead to changes in the phenotype bc it changes the protein made and it leads to a different phenotype.
There is a specific mutation called polyploidy that will reduce gene flow between mutant and wild-type individuals, and it does so because mutant individuals have more than two sets of chromosomes. Polyploidy occurs when an error in meiosis or mitosis results in a doubling of the chromosome number. For example, chromosomes in a diploid (2x) species may fail to pull apart during anaphase of mitosis, resulting in a tetraploid cell (4x) instead of a diploid cell. The problem: the gametes formed by diploid individuals are haploids and the gametes produced by tetraploid individuals so when they mate they form a triploid zygote and if it even develops normally and reaches sexual maturity its three homologous chromosomes cant synapse properly so all the gametes will end up with an uneven number of chromosomes so its sterile. Thus when tetraploid and diploid individuals mate they rarely produce fertile offspring and so they are reproductively isolated from each other.
How do the polyploid individuals involved in speciation form?
There are two general mechanisms: 1. Autopolyploid 2. Allopolyploid
Speciation by polyploidization is driven by chromosome-level mutations and occurs in sympatry. Compared to the gradual process of speciation by geographic isolation or by disruptive selection in sympatry, speciation by polyploidy is virtually instantaneous. It is fast, sympatric, and common.
What happens when isolated populations come into contact? If theres no prezygotic isolation then they mate. The simplest outcome is that the populations fuse over time, as gene flow erases any distinctions between them. Several other possibilities exist.
• The distinctions between the populations may be reinforced if hybrids have low fitness.
•Hybrid zones may be established if hybrids have intermediate fitness.
• Speciation by hybridization may occur if hybrids have high fitness.
If two populations have diverged extensively and are distinct genetically, it is reasonable to expect that their hybrid offspring will have lower fitness than their parents. The logic here is that if populations are well adapted to different habitats, then hybrid offspring will not be well adapted to either habitat.
So if hybrids have a lower fitness, then making the hybrids is a wasted effort! So pre-zygotic isolation behaviours should be favoured, so any traits that promote this behaviour would be favoured by natural selection, and natural selection for traits that isolate populations in this way is called reinforcement.

significance of polyploidy

-increase in cell size
-larger plant attributes
-evolution: may give rise to new species

Speciation

the formation of new and distinct species in the course of evolution.

Macroevolution

large-scale evolutionary changes that take place over long periods of time

habitat isolation

populations are isolated because they breed in different habitats.

Differentiate between the following terms and their use in constructing phylogenies; identify examples of each:

homology (homologous) - similarities in traits due shared ancestry
Can be used to construct phylgoenies because they are from the same ancestor
Analogy - similarities in traits that is not due to a shared ancestry but rather is the result of convergent evolution
Can be useful to understand the functional adaptations of different organisms and construct phylogenies
Analogous - term used to describe similarity in tritas that are not evolved through common ancestry. They are similar in function however, ex. Wings in birds and bats.
homoplasy (homoplasious) - refers to similarity in traits that are not due to shared ancestry but rather the result of convergent evolution or other evolutionary ways.

homology (homologous

similarities in traits due shared ancestry

Analogy

similarities in traits that is not due to a shared ancestry but rather is the result of convergent evolution

Analogous

term used to describe similarity in trAITSas that are not evolved through common ancestry.

homoplasy

A similar (analogous) structure or molecular sequence that has evolved independently in two species.

Explain how the term 'species' can vary between groups of organisms. Compare and contrast the four main species concepts, addressing their uses and limitations. Given a scenario, determine which species concept would be most appropriate to determine if two organisms were the same species

Species are a group of organisms because different species may have different criteria for determining whether they are from the same species or just two different species that may have similar characteristics. Generally, a species is a group of organisms that can interbreed and produce fertile offspring, but there are certain exceptions.

Describe and recognize examples of prezygotic and postzygotic isolating mechanisms. Identify pre-zygotic mechanisms that inhibit mating attempts, and those that limit fertilization, but not mating attempts.

Prezygotic isolation (before the zygote forms) is isolation which prevents individuals from different species from mating successfully. There are different types of prezygotic isolation, such as: temporal, habitat, behavioural, gametic barrier, and mechanical. Some of these prevent mating from even occurring and some prevent fertilization after mating has occurred. Mechanisms that inhibit mating attempts: temporal, habitat, behavioural. Mechanisms that limit fertilization: gametic barrier and mechanical.
Postzygotic isolation: after the zygote has formed, isolation in which the hybrid offspring of matings between members of different species either don't survive or cannot reproduce. There are two types: hybrid viability and hybrid sterility.

Prezygotic isolation

(before the zygote forms) is isolation which prevents individuals from different species from mating successfully. There are different types of prezygotic isolation, such as: temporal, habitat, behavioural, gametic barrier, and mechanical. Some of these prevent mating from even occurring and some prevent fertilization after mating has occurred. Mechanisms that inhibit mating attempts: temporal, habitat, behavioural. Mechanisms that limit fertilization: gametic barrier and mechanical.

Postzygotic isolation

after the zygote has formed, isolation in which the hybrid offspring of matings between members of different species either don't survive or cannot reproduce. There are two types: hybrid viability and hybrid sterility.

Compare two geographic modes of speciation (allopatric and sympatric), identifying situations that could lead to each, and referring to microevolutionary processes; identify examples of each type of speciation. [Knowledge, Comprehension, Analysis]

Allopatric -
occurs when populations of a species are geographically isolated from each other and diverge over time due to different selective pressures or genetic drift.
This can occur due to natural barriers like mountains, oceans, or rivers that physically separate populations, or due to human-caused changes to the landscape like habitat fragmentation or introduction of non-native species.
In allopatric speciation, reproductive isolation can gradually develop between the separated populations due to genetic changes that occur in each group over time. If the populations are reunited, they may no longer be able to interbreed successfully, even if they are brought back into contact.
Allopatric speciation is often driven by microevolutionary processes such as mutation, genetic drift, and natural selection acting on the separated populations.
Example
emergence of Darwin's finches in the Galapagos Islands.
The finches are believed to have originated from a single ancestral population that arrived on the islands millions of years ago.
Over time, the finches became isolated from each other due to geographic barriers such as mountains, leading to the development of distinct subspecies with different beak sizes and shapes that were adapted to their specific ecological niches.
Sympatric -
occurs when new species emerge within the same geographic area without any physical barriers separating the populations.
This can occur due to a variety of mechanisms, such as disruptive selection, polyploidy, or ecological differentiation
In disruptive selection, divergent selection pressures favor different traits within a population, leading to the emergence of two or more subpopulations with distinct traits.
In polyploidy, a rare event in which an organism gains an extra set of chromosomes, can create a reproductive barrier between the polyploid individual and its parental population, leading to the emergence of a new species.
Ecological differentiation can occur when populations exploit different resources or niches within the same geographic area, leading to reproductive isolation over time.
An example of sympatric speciation is the emergence of the apple maggot fly in North America. The fly originally fed on hawthorn berries, but after the introduction of apples, some populations began to specialize on this new resource. Over time, reproductive isolation between the hawthorn-feeding and apple-feeding populations developed, leading to the emergence of two distinct species.

Allopatric

occurs when populations of a species are geographically isolated from each other and diverge over time due to different selective pressures or genetic drift.

Sympatric

occurs when new species emerge within the same geographic area without any physical barriers separating the populations.

How can sympatric speciation occur?

polyploidy, habitat differentiation, sexual selection

Explain the significance of polyploidy, chromosomal alterations (e.g., rearrangements, duplications), and hybridization in speciation.

Chromosome alterations are chromosomal mutations that involve the mutation of a long segment of DNA. Sometimes this alteration could lead to changes in the phenotype bc it changes the protein made and it leads to a different phenotype.
There is a specific mutation called polyploidy that will reduce gene flow between mutant and wild-type individuals, and it does so because mutant individuals have more than two sets of chromosomes. Polyploidy occurs when an error in meiosis or mitosis results in a doubling of the chromosome number. For example, chromosomes in a diploid (2x) species may fail to pull apart during anaphase of mitosis, resulting in a tetraploid cell (4x) instead of a diploid cell. The problem: the gametes formed by diploid individuals are haploids and the gametes produced by tetraploid individuals so when they mate they form a triploid zygote and if it even develops normally and reaches sexual maturity its three homologous chromosomes cant synapse properly so all the gametes will end up with an uneven number of chromosomes so its sterile. Thus when tetraploid and diploid individuals mate they rarely produce fertile offspring and so they are reproductively isolated from each other.
How do the polyploid individuals involved in speciation form?
There are two general mechanisms: 1. Autopolyploid 2. Allopolyploid
Speciation by polyploidization is driven by chromosome-level mutations and occurs in sympatry. Compared to the gradual process of speciation by geographic isolation or by disruptive selection in sympatry, speciation by polyploidy is virtually instantaneous. It is fast, sympatric, and common.
What happens when isolated populations come into contact? If theres no prezygotic isolation then they mate. The simplest outcome is that the populations fuse over time, as gene flow erases any distinctions between them. Several other possibilities exist.
• The distinctions between the populations may be reinforced if hybrids have low fitness.
•Hybrid zones may be established if hybrids have intermediate fitness.
• Speciation by hybridization may occur if hybrids have high fitness.
If two populations have diverged extensively and are distinct genetically, it is reasonable to expect that their hybrid offspring will have lower fitness than their parents. The logic here is that if populations are well adapted to different habitats, then hybrid offspring will not be well adapted to either habitat.
So if hybrids have a lower fitness, then making the hybrids is a wasted effort! So pre-zygotic isolation behaviours should be favoured, so any traits that promote this behaviour would be favoured by natural selection, and natural selection for traits that isolate populations in this way is called reinforcement.

Explain the significance of polyploidy

There is a specific mutation called polyploidy that will reduce gene flow between mutant and wild-type individuals, and it does so because mutant individuals have more than two sets of chromosomes. Polyploidy occurs when an error in meiosis or mitosis results in a doubling of the chromosome number.

temporal isolation

populations are isolated because they breed at different times.

behavioural isolation

populations do not interbreed because their courtship displays differ. Ex. females only recognize the songs of the males of their species

mechanical isolation:

Matings fail because male and female reproductive structures are incompatible.

gametic isolation

Matings fail because eggs and sperm are incompatible

hybrid inviability:

Hybrid offspring do not develop normally and die as embryos.

hybrid sterility and hybrid breakdown;

Hybrid offspring mature but are sterile as adults.

Biogeography

Study of past and present distribution of organisms

genetic isolation

the lack of interbreeding or little genetic mixing between organisms of the same species - results from lack of gene flow

genetic divergence

the evolutionary process wherein a population of species diverge into two or more descendant species, resulting in once similar or related species becoming more and more dissimilar - occurs because selection, genetic drift, and mutation proceed independently in the isolated populations

Reinforcement

natural selection for traits that isolate populations and prevent them from interbreeding

Hybrid zone:

a geographic area where interbreeding occurs and hybrid offspring are common

Cline

A cline refers to the gradual variation in a particular trait or set of traits across the geographic range of a species. For example, a species of bird may have different colored feathers, with individuals in the northern part of its range having darker feathers than those in the southern part. Clines can be the result of natural selection acting on the populations in different environments, with certain traits being favored in one area over another.

Dispersal

when small groups of individuals colonize a new habitat (form of geographical isolation)

Vicariance

a physical splitting of habitat, when a large, continuous population becomes fragmented into isolated habitats (form of geographical isolation)

Differentiate between background and mass extinctions, particularly in terms of adaptation.

Background extinction
Lower avg. rate of extinction observed when a mass extinction is not occurring
often balanced by the emergence of new species through speciation, and it generally allows for the gradual adaptation of organisms to changing environmental conditions over long periods of time.


Mass extinction:
Rapid extinction of a large number of lineages scattered throughout the tree of life
Mass extinctions can also create new ecological opportunities and adaptive radiation, as the survivors of the extinction event exploit new niches and evolve new traits to fill the gaps left by the extinct organisms

Adaptations:
Background extinctions generally allow for the gradual adaptation of organisms to environmental changes, as new mutations and variations are selected for over time.

- Mass extinctions can create selective pressures that are so severe and sudden that many organisms cannot adapt fast enough to survive. This can lead to the extinction of species and clades that were well-adapted to the previous environment, and the emergence of new species and clades that are better adapted to the new environment.

Background extinction

Lower avg. rate of extinction observed when a mass extinction is not occurring
often balanced by the emergence of new species through speciation, and it generally allows for the gradual adaptation of organisms to changing environmental conditions over long periods of time.

Mass extinction

Rapid extinction of a large number of lineages scattered throughout the tree of life
Mass extinctions can also create new ecological opportunities and adaptive radiation, as the survivors of the extinction event exploit new niches and evolve new traits to fill the gaps left by the extinct organisms

Explain and identify circumstances/conditions (i.e., ecological opportunity, morphological innovation) that may promote adaptive radiation, and the hallmarks of adaptive radiation. Illustrate adaptive radiation on a phylogenetic tree. [Comprehension, Application, Analysis]

Adaptive radiation

Where single ancestral species evolve into multiple descendant species that occupy different niches or habitats

Ecological opportunity: this can occur when a habitat or area is unoccupied and is available for colonization. This could be due to changes in the environment or if competitors are not around. Ex. the extinction of dinosaurs paved the way for other mammal species to evolve because the dominant forms (dinosaurs) were not there.

Morphological innovation: when new traits allow ancestral species to exploit resources and/or environments. This gives them an advantage as well. For example, the wings of birds evolved that allowed them to fly and diversify.

Ecological opportunity

this can occur when a habitat or area is unoccupied and is available for colonization. This could be due to changes in the environment or if competitors are not around.

Morphological innovation

when new morpho traits allow ancestral species to exploit resources and/or environments. This gives them an advantage as well.

Hallmarks of adaptive radiation

Rapid speciation - adaptive radiation is characterized by rapid increase of species over a small period of time
Ecological diversification - adaptive radiation results in many species evolving that are adapted to different ecological niches and habitats
Adaptive radiation can lead to the evolution of species that are morphologically or genetically different from each other
convergent evolution

Rapid speciation

adaptive radiation is characterized by rapid increase of species over a small period of time

Ecological diversification

adaptive radiation results in many species evolving that are adapted to different ecological niches and habitats

what can adaptive radiation lead to?

the evolution of species that are morphologically or genetically different from each other

Explain the relationship and temporal pattern between mass extinctions and adaptive radiation. [Comprehension]

The relationship and temporal pattern between mass extinctions and adaptive radiation is that mass extinctions can create ecological opportunities for species and adaptive radiation.

Since the survivors of the extinction event exploit new niches and evolve new traits to fill the gaps left by the extinct organisms, they are able to evolve in the unoccupied niches.

The temporal pattern between mass extinction and adaptive radiation would be the pattern of extinction and rapid diversification of diverse organisms

Explain how exaptation and its role in morphological innovation (traits) can account for the evolution of complex structures (e.g., camera eye, flight feathers, or behaviours). [Comprehension]

Exaptation: traits such as wings, feathers etc didnt appear suddenly, in their full form and function that we see today and it may be quite different than the function of that trait during its evolutionary history for example the original function of the feather may have been insulation and its new function is flight. If natural selection selected for feathers that helped birds fly and it had some sort of benefit then that trait would increase over generations. This is how complex structures developed. (through natural selection because they provided some benefit)

exaptation

shaping of a useful feature of an organism by natural selection to perform one function and the later reshaping of it by different selection pressures to perform a new function

Explain the importance of gene and genome duplication to the evolution of new phenotypes and speciation

Gene duplication when it is not deleterious can have potential phenotypic effects. It may lead to different than normal development but still be beneficial. The duplicated gene may retain original function but change in expression pattern leading to new tissues and developmental timing. Another outcome would be that the duplicated genes gain mutations and alter the protein product which could perform a valuable new function. These two outcomes could lead to the evolution of new traits which is the evolution of new phenotypes and would drive speciation.

Other outcome: duplicated gene retains original function and provides additional quantities or the mutation may prevent expression so a pseudogene is created which is a gene that produces nothing

Explain how different species may have the same gene(s) coding for a particular body part or morphology but have very different body plan (i.e., how genetic changes impacting development underpin evolutionary change).

A small number of genes control the body plans of all animals which are basically the genetic tool kit. Transcription factors (TF) and other proteins bind to specific regulatory sequences in the core and regulatory promoters. Changes in the regulation of the genes expression would result in different species having different features. For example the marine sticklebacks have spines while lake sticklebacks dont, and this is because of changes in the regulation of the Pitx1 expression in the two fish. So while they do have the same genes coding for a particular body part they have a different body plan. They would have inherited these genes from a common ancestor.

Explain how differences in development may lead to divergence and speciation. [Comprehension]

Hox genes are homeotic genes that control head to tail organization of the body and are part of the genetic tool kit. They will basically code for transcriptional factors that control when and where other genes are expressed. Changes in Hox expression are linked to large differences in body structure between different animal groups.The genes need to be expressed at specific times, if for example foot growth ends sooner then the tree-dwelling salamander will have smaller limbs whereas for the ground-dwelling salamander its longer so their limbs are bigger. This is an example of divergence and speciation due to changes in expression at the time of development.

What are hox genes?

they help determine the head to tail axis in embryonic development, and there are found in almost all multicellular organism

Explain how allometry and heterochrony can lead to morphological differences in closely related species, identifying examples of each.

If different parts of the body are growing at different rates like the human head grows slower than the rest of the body. Timing is everything because if there are changes in regulation of developmental genes this could have an effect on morphology - slower development could lead to a totally different morphology. For example salamander teens live in aquatic environments and adults live on land.
Heterochrony is changes in the timing of developmental events between closely related species for example the salamander and the axolot. They retain their juvenile features even as adults because of a mutation in a certain genes expression.

What is allometry?

the growth of body parts at different rates, resulting in a change of body proportions

What is heterchrony?

is defined as a developmental change in the timing or rate of events, leading to changes in size and shape. There are two main components, namely 1) the onset and offset of a particular process, and 2) the rate at which the process operates.

Apply knowledge of microevolution, phylogenetics, and speciation (see sections D, E, & F) to concepts/problems of macroevolution, including understanding of key innovations in vertebrate evolution.

Phylogenetics - By constructing phylogenetic trees based on genetic and morphological data, scientists can infer the sequence of evolutionary events that led to the diversification of different groups of organisms.

Speciation (allopatric and sympatric) - These processes can lead to the formation of new species and the diversification of groups of organisms over time.

Macroevolutionary processes build on microevolutionary processes and involve the evolution of major groups of organisms over long periods of time

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species

ecological opportunity

the availability of new or novel types of resources

homeotic genes

Genes that determine basic features of where a body part is.

transcription factors

are proteins that control the rate of transcription of genetic information from DNA to RNA.

segment

part of an organism's body or a section of a chromosome that contains genes.

regulatory genes

genes that control the expression of other genes

Homeosis

replacement of one body part with another during development

regulatory cascade

A multistep regulatory pathway in which a signal leads to activation of a series of proteins in succession, with each protein in the succession catalytically activating the next, such that the original signal is amplified exponentially.

evolutionarily conserved

Characteristics that persist relatively unchanged through diversification of a group of organisms and therefore remain similar in related species.

differentiate/differentiation

the process by which a less specialized or unspecialized cell becomes more specialized in order to carry out a specific function.

Vertebrae

26 small bones that make up your backbone

Cranium

skull

Cartilage

A connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together.

endoskeleton vs exoskeleton

Endoskeleton refers to a skeleton that is located inside the body, while exoskeleton refers to a skeleton that is located outside the body.

Gnathostomes

jawed vertebrates

Amniotes vs. Anamniotes

Anamniotes are animals that do not lay amniotic eggs, while amniotes are animals that lay amniotic eggs.

amniotic egg

an egg that is surrounded by a membrane, allowing for development on land.

gill arches

bony or cartilaginous structures that support the gills of fish and some amphibians.

pharyngeal jaws

second pair of jaws in the throat in some fish

gestation

growth process from conception to birth

allometric growth

Proportioning that gives a body a specific form.

metamorphosis

process of transformation from one life stage to another, such as a caterpillar becoming a butterfly.

Pseudogenes

a gene that has lost its function and is no longer expressed.

Describe key adaptations that distinguish humans from non-human primates,

Bipedalism
Large brain
Smaller jaw and teeth

traits formerly attributed only to humans that are found in other species.

Tool use
Culture
Self-awareness
Language

Describe an example of natural selection in humans

- Development of
lactose tolerance

Ability to digest lactose declines after weaning

Genetic mutation has arised that has allowed many humans to digest lactose

This mutation has become advantageous
Some people still cannot digest lactose

Explain to an individual with little science background why humans are more correctly described as 'sharing common ancestry with chimpanzees', rather than the incorrect 'descended from chimpanzees.'

Humans and chimpanzees are both primates that have a common ancestor many millions of years ago. They share many similarities, but humans did not DESCEND from chimpanzees. For example, humans and chimpanzees could be cousins that share grandparents, but they don't have the same parents. Cousins can look alike too and have similar characteristics, but that does not mean that they have the same parents. Likewise, humans and chimpanzees shared a common ancestor very very long ago, but they humans did not come or evolve from chimpanzees.

Explain and describe the evidence, from both humans and other organisms, supporting African ancestry of hominins,

- Anatomical evidence
Most primitive fossils were found in central and east africa, indicating that that was the region of the ancestral home of the hominins

- Genetic evidence
Greatest genetic diversity is found in Africans

describe the migration pattern of humans over their evolutionary history, relating evidence to founder events.

Migration patterns

Can be traced through fossil and genetic evidence
- Homo erectus - evolved when early hominins moved out of Africa
- Homo neanderthalensis - evolved when second migration occurred to Europe

Genetic evidence
- Genetic markers of neanderthalensis were different from african populations