BIOL 1450 Exam 3

evolution

change in the distribution of heritable phenotypes

microevolution

changes in distribution of heritable phenotypes in a population

speciation

evolutionary process by which new species arise

phenotype

physical and functional charecteristics of an organism

phenotypic variation

differences in appearance or function that are passed from generation to generation

heritable trait

trait that is passed from parent to offspring, due to genes

gene

specific sequence of DNA that spells out instructions to make a particular product

genetic variation

differences among individuals in the composition of their genes or other DNA segments

biological species concept

can mate or potentially mate in nature, and offspring are able to survive and reproduce

morphological species concept

share similar characteristics or traits

phylogenetic species concept

smallest group of organisms with all known descendants of a common ancestor-- distinguished from other species by unique traits

gene flow

exchange of genes between populations

reproductive barrier

heritable traits that limit/prevent mating

prezygotic barrier

before fertilization

postzygotic barrier

after fertilization

list all types of prezygotic barriers

behavioral, habitat, temporal, mechanical, gametic

list all types of postzygotic barriers

reduced hybrid viability, reduced hybrid fertility

behavioral barrier

have diff mating behaviors; do not recognize each other as mates

habitat barrier

live in same area, but occupy different habitats; do not encounter each other to mate

temporal barrier

mate at diff times

mechanical barrier

physical barrier to bringing egg and sperm together

gametic barrier

sperm cannot fertilize egg

reduced hybrid viability

hybrid offspring don't survive well enough to have their own offspring; may not develop well

reduced hybrid fertility

hybrid offspring cannot successfully reproduce

allopatric speciation

speciation that occurs with geographic isolation

sympatric speciation

speciation that occurs when populations live in the same area, often due to differences in habitat or mate preferences

phylogenetics

study of evolutionary relationships b/w organisms

phylogenetic trees

visual representations of evolutionary relationships b/w groups of organisms

phylogeny

evolutionary history of a species

taxa

defined groups of organisms; can be thousands of species or one species

internal node

common ancestors

outgroup

distantly related taxon; can help predict patterns of trait evolution

clade

all taxa that are descendants of a shared common ancestor; any group that can be separated with one snip

character

heritable characteristic of an organism

homologous trait

similar traits due to shared ancestry

analogous trait

evolved in diff lineages; similar traits due to convergent evolution

convergent evolution

independent evolution of similar traits often due to shared environmental conditions/requirements

maximum parsimony

assumes that hypotheses requiring fewer evolutionary changes are more likely to show true evolutionary patterns

character state

version of a trait

what is the challenge with constructing phylogenetic trees?

a character may not be useful for determining evolutionary relationships

shared traits may not always reflect

shared ancestry: analagous traits

what does branching represent?

hypothesized splitting/speciation

can phylogenetic trees change?

Yes, they can and will change as they are just hypotheses.

what are the different types of data used to construct a phylogenetic tree?

morphological, molecular, developmental, behavioral

degree of evolutionary relatedness is determined by

number of shared ancestors

why can evolutionary change not lead to organisms perfectly suited to their environment?

traits have trade offs, environmental conditions change, constrained