bio ch22 intro to evolution

key concepts: overview of evolution, evidence of evolutionary change, the molecular processes that underlie evolution

evolution

heritable change in one or more characteristics of a population or species from one generation to the next

microevolution

changes in a single gene in a population over time

macroevolution

formation of new species or groups of species

empirical thought

relies on observation to form an idea or hypothesis rather than trying to understand life from a non-physical or spiritual pov

species

group of related organisms that share a distinctive form and are capable of interbreeding to produce viable and fertile offspring (among sexually reproductive species)

population

members of the same species that are likely to encounter each other and thus have the opportunity to interbreed

catastrophism

earth is old and was shaped by sudden, violent events

uniformitarianism hypothesis

slow geological processes lead to substantial change, earth was much older than 6k years

charles darwin

noticed distinctive traits of island species that allowed them to better exploit their environment. “survival of the fittest”

evolution is based on what two things?

variation within a given species and natural selection

variation

traits heritable, genetic basis not yet known

natural selection

more offspring produced than can survive, which leads to competition for limited resources. individuals with better traits flourish and reproduce

what are five pieces of evidence of evolutionary change?

fossil record, biogeography, convergent evolution, selective breeding, homologies

what are three types of homologies?

anatomical, developmental, molecular

selective breeding

programs and procedures designed to modify traits in domesticated species, aka artificial selection.

how are parents chosen in selective breeding?

parents chosen by breeders based on desirable phenotypes

example of selective breeding

dog breeds, brassica plants, corn

biogeography

study of the geographical distribution of extinct and modern species. isolated continents and island groups evolved their own distinct plant and animal communities

what effect did changes in the distribution of land masses on earth have on life?

evolution of major animal groups

convergent evolution

two different species from different lineages show similar characteristics because they occupy similar environments, species are not closely related evolutionarily

fishapo (Tiktaalik roseae)

illuminates steps leading to the evolution of tetrapods. it is a transitional form and provides a link between earlier and later forms

physical characteristics of the fishapod

broad skull, flexible neck, eyes on top of head, primitive wrist, five fingers. could peek above water and look for prey

what animals are in the order cetacea?

whales, dolphins, porpoises

how did whales evolve from terrestrial mammals?

they went from being terrestrial tetrapods to aquatic animals lacking hind limbs

homology

fundamental similarities due to descent from a common ancestor

anatomical homology

same set of bones in the limbs of modern vertebrates has undergone evolutionary change for many different purposes

what are homologous structures derived from?

common ancestor

vestigial structures

anatomical structures that have no apparent function but resemble structures of presumed ancestors (ex. ear wiggling muscles)

developmental homology

species that differ as adults, but bear striking similarities during embryonic stages (ex. presence of gill ridges and long bony tails in human embryos)

molecular homology

similarities in cells at the molecular level show that living species evolved from a common ancestor. all living species use DNA to store info, certain biochem pathways are found in all or nearly all species

the same type of gene is often found in…

diverse organisms

homologous genes

two genes derived from the same ancestral gene. reveals molecular details of evolutionary change

paralogs

homologous genes within a single species

gene family

two or more paralogs within the genome of a single organism. caused by gene duplication

horizontal gene transfer

exchange of genetic material among different species

when can horizontal gene transfer occur?

prokaryotes to eukaryotes, eukaryotes to prokaryotes, between prokaryotes, between eukaryotes. widespread among bacteria

how does evolution occur at the genomic level?

changes in the chromosome structure and number