Evolution with Common Descent

What is evolution?

The change in genetic makeup of a population over time.

What is a mutation?

A change in genetic code that serves as the ultimate source of genetic variation in a population.

What is genetic variation?

Differences in individual DNA that lead to variations in RNA, proteins, and ultimately phenotype.

What is phenotype?

The expression of genetic code (DNA) and genotype that results in observable traits.

How does the environment affect phenotype?

phenotype variation results from a mutation that was advantageous to said environment

Genotype

Combination of two alleles, either recessive or dominant, found in genome

What is natural selection?

A mechanism of evolution that explains how inherited traits that provide a survival advantage become more common in a population.

What are the requirements for natural selection to occur?

There must be variation in inherited traits, and some traits must confer a higher probability of survival and reproduction.

What is an adaptation?

Any trait that increases an individual's ability to survive and reproduce compared to others in the population.

What are genes?

Segments of DNA that code for specific traits in an individual.

What are alleles?

Alternate forms of a given gene.

What is the difference between homozygous and heterozygous?

Homozygous means having two identical alleles, while heterozygous means having one of each allele.

What is the Sickle Cell Trait (SCT)?

A genetic trait that provides an advantage in malaria-prone areas by causing some red blood cells to sickle in low oxygen environments.

Why is SCT and other red blood cells diseases affective against malaria?

Malaria reproduces in blood cell, in people with the SCT trait specifically their blood cells sickle because malaria uses oxygen to survive

SCT vs SCT trait

SCT means you are homozygous for the recessive SCT alleles meaning you have the disease. Meanwhile the SCT trait means your heterozygous and just a carrier.

How does lactose intolerance relate to evolution?

Lactose persistence beyond childhood is due to mutations in regulatory genes, advantageous in pastoral populations that rely on milk.

What is an example of co-evolution of humans w/ culture

Evolution of Lactose tolerant people

What does it mean if different mutations having the same outcome are present in different populations?

mutations arose independently

What is common descent?

The concept that all living organisms are related and change over time through descent with modification.

What evidence supports evolution and common descent?

Fossil records

embryology

direct observation of evolutionary change

homology

biogeography

What is comparative anatomy?

The study of differences and similarities in the anatomy of organisms to understand evolutionary relationships.

What is embryology & Development

how creature develops before being born/ hatched in an egg

What is homology?

Having the same or similar traits, genes, or structure in different species that are inherited from a common ancestor

What are vestigial structures? (homology)

Remnants of structures that served important functions in an organism's ancestors but are no longer functional

What is an example of a vestigial structure in humans?

The coccyx (tailbone), which corresponds to the functioning tail of our ancestors

What is molecular homology?

All life shares a common genetic language (DNA & RNA), with similar DNA sequences indicating how close they're evolutionary relationship is

Why can't guinea pigs, humans, and great apes synthesize vitamin C?

They lack the enzyme Gulo, which converts glucose into vitamin C due to a mutation.

What is the role of DNA in evolution?

DNA sequences can be compared among species to determine common ancestry and evolutionary relationships

What is direct observation in the context of evolution?

Observing rapid changes in populations, such as bacteria developing drug resistance, to study evolutionary processes.

What is descent with modification?

The process by which organisms change over time, leading to the diversity of life we see today.

What is a frame shift mutation?

both nucleotide pairs are missing, causing the entire sequence to shift and potentially leading to a premature stop codon.

What is a point mutation?

A mutation where one nucleotide pair is substituted by the wrong one, causing RNA to read a stop codon prematurely.

What is biogeography?

study of the distribution of living organisms across the Earth

What does biogeography explain about island species?

It shows that island species are often closely related to mainland species, suggesting a common ancestor.

Why do islands have a large variety of species

Colonizing species give rise to new species as they adapt to the new environment

What is a species?

A group of individuals that can exchange genetic material through interbreeding or shared alleles through reproduction.

What is a gene pool?

consists of all the alleles present in all individuals in a species.

What defines a population in biology?

an interbreeding group of organisms of the same species living in the same geographic area.

What is the Biological Species Concept (BSC)?

To be the same species individuals must be reproductively compatible and produce fertile offspring

What is the Morphospecies Concept?

States that members of the same species often look alike, useful for field studies despite its limitations.

Why is the Morphospecies Concept flawed?

Individuals of same species may look different due to variance and different species can look similar.

What are the three steps necessary for speciation?

1. Isolation of gene pools of two or more populations

2. Evolutionary change in one or both gene pools

3. Reproductive isolation preventing gene flow

Prezygotic Barriers

Impede mating or hinder fertilization

What is ecological isolation?

Species occupy different habitats, preventing mating without a physical barrier.

(Prezygotic)

What is temporal isolation?

Species breed at different times, preventing gamete exchange.

(Prezygotic)

What is behavioral isolation?

Species have specific mating behaviors that must be performed for reproduction to occur.

(Prezygotic)

What is mechanical isolation?

Genitalia of different species do not fit together, preventing mating.

(Prezygotic)

What is gamete isolation?

Sperm and egg of different species cannot successfully fertilize each other. Ie. sponges have receptors on eggs permitting only sperm of same species to enter

(prezygotic)

What are postzygotic barriers?

mechanisms that occur after the formation of a zygote (fertilized egg)

What is reduced hybrid viability?

Hybrid offspring do not develop properly or are weak and die early.

What is reduced hybrid fertility?

Hybrid offspring are sterile, such as mules produced from horses and donkeys.

What is hybrid breakdown?

The first generation of hybrids is viable and fertile, but subsequent generations are weak or sterile.

What is speciation?

Single interbreeding pop. is split into two and diverge generically overtime, becoming different species

What is allopatric speciation?

Speciation that occurs when populations are separated by a geographic barrier, leading to genetic divergence.

What is dispersal in the context of speciation?

A process where individuals colonize new areas, leading to the formation of new species.

Allopatric speciation

What is vicariance?

A process where a geographic barrier arises, splitting a population and leading to allopatric speciation.

Ring species

example of vicariance speciation where a species is separated by physical barrier and loops back around at the end as different species

What is sympatric speciation?

Speciation that occurs in populations that share the same geographic area, often due to habitat differentiation (ie. living in different kinds of trees)

How many mutations are needed to lead to speciation?

The number or mutations doesn't matter.

In Japanese land snails only one mutation is needed for speciation while the sunflower hybrid has 26.

Speciation to Macroevolution

accumulation of mutations and speciation leads to evolution

What is convergent evolution?

The independent evolution of similar traits in different lineages, resulting in analogous structures without a recent common ancestor.

What is divergent evolution?

the process where two groups of organisms from a common ancestor accumulate differences, leading to new species

What is macroevolution?

The accumulation of genetic changes over time that leads to the formation of new groups of species that differ significantly from their ancestors.