BILD 3 Exam 1

Reproductive Isolation

the existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring

impede us from knowing if they are a species based off of the biological species concept that says a species is a species if it has the potential to interbreed and produce viable offspring

-so therefore it is a roadblock to new species because it hinders interbreeding

-blocks gene flow which hinders the two populations to become more alike each other and doesn’t allow for hybrids to come about

Biological Species Concept

a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring—but do not produce viable, fertile offspring with members of other such groups

speciation can occur: by the evolution of reproductive isolation

Ecological Species Concept

defines a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment (see

Morphological species concept

distinguishes a species by body shape and other structural features

Prezygotic Barriers

a barrier that hinders the breeding process between two species can or prevents the completion of the fertilization process if mating does occur

Habitat Isolation: when species occupy to different habitats so they don’t even come across each other to be able to breed

Temporal Isolation: when species breed during different times, seasons, years

Behavioral Isolation: when there is a difference in courtship rituals

Mechanical Isolation: when two species are unable to interbreed due to differences in morphological structures

Gametic Isolation: when the sperm of one species is unable to fertilize the egg of another species

Postzygotic barriers

stops a hybrid individual from becoming a viable and fertile adult

Reduced Hybrid Viability: the genes of the parents combine in a way that hinders the hybrid's development and ability to survive in the environment  

Reduced Hybrid Fertility: different numbers from the parent species doesn't allow it to  to produce offspring 

Hybrid Breakdown: that current hybrid is viable and fertile, but when they mate the next generation is not

Allopatric Speciation

Speciation that occurs due to a geographical barrier that separates a population into subpopulations 

• The divide leads to accumulation of differences caused by mutations, natural selection, and genetic drift 

• This leads to reproductive isolation

• This can be caused by mountain ranges coming up or rivers splitting off into 2 streams 

• Or migration onto a far-off, secluded island [ a prexisting barrier] where genetic drift and founder effect occur strongly( due to smaller size of the population)

• Galapagos Finch: they colonized an island and they are separated geographically and then they diverged into multiple different species; each adapted to a different local environment 

Sympatric Speciation

speciation that occurs in populations that live in the same geographic area 

• can occur if gene flow is reduced by such factors as polyploidy, sexual selection, and habitat differentiation (when a subpopulation exploits a habitat or resource not used by the parent population.). 

• Plants are mor likely to go through sympatric speciation due to polyploidy (a mutation that causes an organism to have more chromosomes than normal). Plants can go through this and survive while it is not as likely for animals. This is because they can produce asexually  

Evolution

the accumulation of differences from their ancestors as they adapt to different environments over time

change in allele frequency

Change in a population’s heritable traits or gene pool over time

Homologous Trait

a trait that is shared between two species because they share a common ancestor

Convergent Trait

A trait that two species share because it evolved multiple times separately

Came about independently

Lineage

ancestors and their descendants over time. all the species between the common ancestor and the organism we are focusing on

trait

a characteristic that can be measured or observed

Descent with Modification

the pattern of evolution

Descent: common ancestor

Modification: there is a change in heritable traits and this occurs independently

Divergence: the accumulation of differences(mutations, genetic drift, different selected traits due to different environmental pressures) and they become different species

1. As the lineage evolves through time they become more like modern species

2. They look less like each other and their common ancestor

3. They diversify into multiple species9doversification)

Struggle for existence

many offspring die before they can reproduce

which is why big growth potential is only potential because of limiting factors(predation, habitat loss, pathogens, pollutions)

Natural Selection

occurs when there is variation in a trait that improves the likelihood of survival and reproduction; a trait where those who have it are more likely to survive and reproduce

does each animals have the same likelihood of surviving no? a trait has variation and if it helps survival then naturally those who do not have it die, and then it gets selected and evolves in the species

changes populations not individuals(it is filter) your not gonna see the effect in one individual because it is an average and it occurs over time

changes allele frequencies, increasing the frewuency of advantageous ones and decreasing the non advantageous ones

Evolution by natural selection occurs when there is variation in a heritable trait

Genetic Drift

random events that drastically change the size of a population: habitat destruction, wildfires, (bottleneck effect) ; changes allele frequencies rather they are advantageous or not

Gene Flow

when a group from a population either moves in or out of an area bringing with them new alleles or removing them when they leave. this changes allele frequencies leading and creates diversity

Non-random mating

when individuals choose their partners based off of specific traits, inbreeding, genotype prevalences change in the population ; changes the percentages of homozygotes and heterozygotes in a population; alters genotype frequencies rather than allele frequencies so it is not as strong as genetic drift or natural selection

Darwin’s argument for natural selection

Observation #1: individuals of the same population have varied inherited traits

Observation #2: individuals produce more offspring then the environmental can sustain so not everyone survives and reproduces

Inference #1: if have an inherited trait that increases your likelihood of survival and reproduction you are more likely to have more survived offspring

Inference #2: This unequal ability for an organism to survive will lead to the accumulation of favorable traits in the population over time

Darwin’s Theory of Evolution

Pattern: Descent with Modification

Process: Natural selection

England and Europe Beliefs 1800s

• special creation- God created each individual animal and as they are was how they were made; they didn’t descend from anything

• The earth is older than 6000 years old but don’t know exactly how old

• Paleontologists found fossils so they knew there was change over time(pattern) but the process that were causing it

Darwin’s observations and finds

Argentina

• Darwin found a fossil of an extinct big mammal and so that it was very similar to present day animals that occupied the area

• Principle of Succession: animals in a region look similar to fossils of that region because that is who they descended from with modification

Chile, Andes Mountains

• fossilized seashells at 12,000ft

• Earthquake and volcanic eruption raised the coastal shelf 8ft

• Charles Lyell- if given enough time these big structures can be made then maybe over time life can change over time

• An old earth means there was enough time for descent with modification to generate the entire tree of life

• DIVERGENCE

Galapagos Islands

• Islands with sparse tall vegetation had tortoises with bumpy shells and long necks/legs

• Islands with thick, low vegetation had tortoises with short necks/legs and soft shells

• Islands with intermediate features had intermediate featured tortoises

• each had features that were best suited for their environment

• Different selection pressures lead to local adaptions by natural selection which lead to more branches on a tree(speciation)

Charles Lyell

Hypothesis for gradual and consistent geological change

The small, observable forces we see today, have caused the big things we see today given enough time. Therefore the earth must be very old becuase we got these big freaking mountains; erosion, sedimentation…

Artificial Selection

the creation of different types of an animal by going from the common ancestor and selecting certain traits

what is desired by humans while natural selection is chosen naturally for an organisms survival and reproduction

How it helped Darwin: If I can breed two things and drastically change their characteristics in a short amount of time, nature can co the same over a long span of time. but for natural selection, nature acts as the filter rather than a human being it for artificial selection. He also noticed that when breeding the offspring naturally inherit from the parent

Adaptive Radiation

when species from a common ancestor diversify(or speciaize) in order to fill different ecological niches. It is a burst of evolution that gives rise to lots of new species: Galapagos Finches and Lemurs

speciation is when one population splits off into 2 reproductively isolated populations

Local adaptation to different environments contributes to divergence between populations and the origin of new species. When this happens repeatedly in one lineage, the result is an adaptive radiation: one species splitting into many species.

Origin of Species Ideas

1. All organisms evolved from a common ancestor via descent with modification and divergence

2. The mechanism was natural selection

Local Adaptation

1. Differential Selection Pressures: different environments favor different traits

Microevolution

smaller scale and we can see it in our lifetime

genetic drift, gene flow, mutation, natural selection

changes in the gene pool

Galapagos beak size, antibiotic resistance

Macroevolution

on a bigger time scale

origin of new species

major changes in traits

evolution, adaptive radiation

Principle of Stratigraphy

sedimentary rocks, where fossils are found, the most recent animal will be found on top while the older more archaic will be found deeper on a lower level

Sedimentary Rock Formation

1. weathering: baby rocks and stuff

2. erosion: wind and water move these sediments to nearby lakes and river where they settle down

3. compaction: other sediments(with animal remains) come and compact each layer cause the weight is heavy and as they do this water and air get pushed out and each layer gets cemented together

4. plant and animal remains become fossilized over time

A fossil rabbit in the Precambrian

this would challenge the idea of descent with modification because there is nothing in the Precambrian for a rabbit to be descended from. It would break the pattern: species evolving over time into other similar species

we haven’t found this but wehave found transitional fossils

Fossil Record: evidence of evolution

• Fossil record with lower strata showing more simpler animals and higher strata showing more complex and more modern organisms Extinction: these animals died and leave behind empty ecological niches giving room for other species to enter and diversify. Animals appearing and disappearing align with environmental pressures showing that macro natural selection is occurring. Shows that life does change over time.

• Transitional Forms: these are intermediate figures that connect an ancestor to its descendent. It reveals that there isn’t a gap or jumping going, life is changing continuously in connection. It shows descent with modification is taking place

• Biogeographical evidence: Darwin’s 3 places he visited

TikTaalik

transitional form that was found

• Tetrapod Similarities: Flat head with eyes on top as well as ribs

• Fish Similarities: Scales and gills

Tetrapod

4 limbed vertebrae anima; back bone and limbs with digits; amphibians , mammals, reptiles

example: lizards

Archaeopteryx

beak and wings like bird and clawed forelimbs with boney tail like reptile

Vestigial Structure

like vegetable state; a trait that is functionless or almost functionless in an organism(functions in another species) but is still present; it was functional in the common ancestor

example: appendix(help digest cellulose), tailbone(a tail to help with balance), wisdom teeth(grind down on tough uncooked foods)

They show that we share common ancestry with those organisms that had the trait fully functioning. It shows that we inherited things from their ancestor

example: Whales have small pelvic bones because their ancestors had hindlimbs they used to walk on land. That remaining pelvic bone is proof they evolved form their ancestor

Anatomical and Molecular homologies

structure is similar due to shared ancestry but functions differently due to modification

Humans use forelimbs for grabbing while whales use them for swimming; this shows that we evolved from a common ancestor though are functions are different because the structures are the same

Developmental hoomology

inherited similarities during development phase though very different lookin gin adulthood

embryos of fish and chicken have the same tails; inherited developmental features from a common ancestor

Molecular Homology

all organims all have the same codons coding the same amino acid; similarities on the molecular level

Humans and chimpanzees share many similar DNA sequences which shows that they inherited genetic information from a common ancestor

Evolution in the past 50 years

Pesticide resistance: general bug killer used and many but due to mutations not everybody died. So those who survived passed down their resistance and the population evolved and developed this resistance

Evolution in genetic terms

change in the gene pool over time

Gene

a small region of a chromosome that codes for a molecule

Allele

versions of a gene

Diploid

have two copies of gene

Genotype

the allels and individual has for a gene

Population

a group of interbreeding individuals

Allele Freequency

all copies of a given gene that have that allele

p+q=1

Microevolution

change in allele frequencies over time

Hardy-Weinberg Equilibrium

when a population is not measurably evolving caused by:

1. No genetic Drift

2. No mutations-source of all genetic variation but is a very slow process

3. No gene Flow- alter allele frequencies in a population by bring in new ones; they reduce genetic differences between the two populations but introduce variation to a genetically drifted population; goes against NS by bringing in non adapted or selected alleles

4. No Natural selection- can select for one genotype against others, changing allele frequencies

5. Random Mating(no inbreeding)-(non random effects genotype frequencies; can produce excees homozygotes(assorttative mating) or excess heterozygotes(disassortative mating)))

the purpose of the test is to see if any of this is happening

Genotype Count

all the individuals in thepopualtion that have the genotype

Genotype frequency

percentage of individuals that have a certian genotype

Gene pool

all genes and alleles in a population

Genetic Drift

change in allele frequencies due to random sampling effects

it is random what alleles will be passed down to offspring, it is random which individuals survive and reproduce

This a loss of genetic variation because as time goes on because of loss of alleles or alleles may become fixed

It is always happening but it is stronger in small populations

works against natural selection as it is random while natural selection is intentional. trying to select the favorable traits and your deleting animals that may have them. less variability for it to be able to select

occurs in every population of any size

Genetic drift arises from sampling error when a finite population passes genes from one generation to the next.

Genetic drift is simply a "sampling error" in how alleles get passed down

Gene Flow

migration, introudicing new allelle or already presetn not as stron alleles to a population. Makes that population similar to the one it came from. Works agaisnt natural selecction as it brings in no adapted alleles.

example: florida pantether was dying so they reintrouced a couple more to the environment which spruced up genetic diversity, brought in new alleles

Mutation

the source of all genetic variation(creates entirely new alleles) and therefore VERY important for evolution and is the permanent change in a DNA sequence(caused by copying errors or environmental factors like radiation)

Mutation rate is too low to have an effect on allele frequencies in the short term and it also rarely happens because there are checks during the copying process that hinder a mutation from becoming permanent; therefore this is probably not a reason for a population to depart from Hardy-Weinberg Equilibrium

Assortative mating

mating based off of similar traits that the other organism has; this increases homozygotes in a population[nonrandom mating]

Disassortative Mating

mating based off of your differences with the other organism; increases heterozygotes in a population[non-random mating]

phylogeny

the evolutionary history of a species

Taxon

a named group on any level of the hierarchy; Panthera is taxon on the genus level and Mammalia is taxon on the class level

Sister Taxa

a group of organisms that share the same common ancestor that others do not share

Clade

a single common ancestor and all its descendent

Parsimonous

the fewest evolutionary events

Topology

branching pattern of the tree; shows you which organisms are more closely related

Sexual Selection

Based off of offspring sometimes at the expense of survival; selection for greater reproduction

Intrasexual selection: Competition between males for mates

Intersexual selection: Choice of the females for males

Leads to sexual dimorphism where the males and females look different

Half-life

the amount of time it takes for half of the atoms of the parent isotope to decay into the daughter isotope

Radioactive Isostopes

decay into other isotopes or elements at a constant rate

• Carbon dating:(also ¹⁴C) Carbon¹⁴ to ¹⁴N; the clock starts at DEATH

  • half-life of ¹⁴C is 5730

  • each half -life is not a lot of time; carbon decays really fast so for those animals who are more than years old, carbon 14 isotope can’t be used for older, older, fossils

  • for recent organic

• Uranium Dating: Uranium 235 and 238(704 my and 4.5 by)

  • for old inorganic

  • Clocks: magma or lava cools and solidifies into rock. the U gets trapped during crystallization, beginning the clock