ap bio unit 7

species

a group of organisms capable of interbreeding and producing viable, fertile offspring

speciation

the process by which one species splits into two or more distinct species

geography

the physical environment/location thay can bar gene flow

prezygotic barrier

a mechanism that prevents fertilization from occurring before the zygote forms

postzygotic barrier

a mechanism that reduces the viability/reproductive capacity of offspring after the zygote forms

allopatric speciation

speciation that occurs when populations are geographically isolated

sympatic speciation

speciation that occurs while populations live in the same geographic region

temporal isolation

species that breed at different times (seasons, time of day, etc.)

behavioral isolation

unique behavioral patterns/rituals (like mating calls or dances) that isolate species

mechanical isolation

physical differences that prefent successful mating

gametic isolation

sperm of one species cant fertilize eggs of another

habitat isolation

two species seperated by habitat in the same area

reduced hybrid viability

hybrid offspring fail to develop/survive

reduced hybrid fertility

hybrid offspring are healthy but sterile (mule)

hybrid breakdown

first-generation hybrids are fertile, but their offspring (could be f2 offspring) are weak/sterile

punctuation equilibrium

evolution that occurs rapidly after long periods of stasis (no change)

gradualism

evolution that occurs slowly and steadily over hundreds of thousands of years

divergent evolution

when adaptation to new habitats results in phenotypic diversification (species branching out)

convergent evolution

unrelated species in different areas evolving similar traits due to similar environmental pressures

macroevolution

large-scale evolutionary changed that occur over long periods, resulting in new groups of organisms

microevolution

small-scale changes in allele frequencies within a population over a short time

adaptive radiation

rapid evolution of many species from a common ancestor when new habitats become available

RNA world hypothesis

a theory that proposes that RNA was the first genetic individual and primary functional molecule in the early stages of life, long before DNA or proteins evolved

cladogram

a diagram used to show relationships between lineages based on shared characteristics

phylogenetic trees

similar to cladograms, but shows the amount of change ofer time, often calibrated by fossils/molecular clocks

systematics

the study of diversification of living forms and their evolutionary relationships

basal taxon

a lineage that evolved early from the root

sister taxon

two lineages that are each others closest relative, arising from the same immediate node

monophyletic group

a group consisting of a common ancestor and all of its descendants

derived characteristic

a trait thats new to a specific clade (not found in the ancestor)

ancestral characteristic

a trait that was present in the common ancestor of the group

synamorphy

a shared, derived characteristic used to define a specific clade

paraphyletic group

a group with a common ancestor but only some of its descendants

polyphyletic group

a group that includes organisms with different common ancestors

parsimony

the princinciple that the simplest explanation (relative to the first evolutionary changes) is the correct one

comparitive morphology

the study of the similarities + differences in the body structures of different species

analogous structures

features in different species that have similar functions but evolved independently (not from a common ancestor), usually due to similar environmental pressures

embryonic homology

similarities in the decelopment of embryoes across different species, suggesting a common ancestor

vestigial structure

remnants of organs/structures that had a function in an early ancestor but now serve little to no purpose (ex: human tailbone)

molecular homology

similarities in DNA, RNA, or ino acud sequences among figferent organisms, indicating they share a common genetic origin

homologous structures

physical features shared by different species because they were inherited by a common ancestor even if they serve different functions now