module 6 Flashcards
what is macroevolution?
above the species level (gives us new species)
what is microevolution?
below the species level (all evolution has been micro thus far)
what is a biological species defined as?
group of naturally breeding populations that are reproductively isolated from other groups
what is speciation?
occurs when one species splits into 2
- involves reproductive isolating mechanism
what is a reproductive isolating mechanism? what does it lead to?
anything that prevents 2 populations from breeding effectively
- leads to speciation
What are the two types of reproductive isolating mechanisms?
- extrinsic: factors producing geographic isolation
- intrinsic: factors unrelated to geographic isolation
what are the 2 kinds of intrinsic reproductive isolating mechanisms?
- prezygotic: zygote never forms
- postzygotic: zygote forms but may have mutation that will cause it to die later
What is the relationship between natural selection & population variability?
the rate of evolutionary change is directly proportional to the degree of variability in a population
(e.g lots of variation –> lots of alleles)
What is the corollary natural selection principle?
the fate of all evolutionary lineages is extinction
what is anagenesis? what theory of evolutionary change does this support?
change in a species over a long period of time (supports gradualism theory of evol. change)
What is cladogenesis? what theory of evolutionary change does it support?
sudden split results in formation of 2 species from 1 species (supports punctuated theory of evol. change)
what is phyletic gradualism?
small changes occur over time & accumulate over a long period of time (anagenic change)
what is punctuated equilibrium?
evolution goes through long periods where nothing changes, but sudden changes occur (cladogenic change)
what is adaptive radiation?
the rapid expansion/diversification of a group of organisms as they adapt to newly available ecological space
what is a generalized organism?
able to live in wide range of habitats
what is a specialized organism?
has defined ecological niche (way of interacting with environment)
what is an overgeneralized organism?
leads to extinction when environment changes bc they can’t adapt well
what is the purpose of phylogenetic relationships?
- determines who is related to whom & how closely
- uses anatomical similarities
what is evolutionary homology?
-similarities between organisms due to common ancestry
- structure might have different function
what is evolutionary analogy?
similarities between 2 organisms that are INDEPENDENTLY EVOLVED
- coincidental
- same function
what are two types of analogy?
- convergence: similarities between 2 UNRELATED organisms
- parallelism: similarities between 2 RELATED organisms (more recent common ancestor
what is a primitive/ancestral trait?
trait retained in its ancestral form
what is a derived trait?
change in ancestral form of a trait (including losing a trait)
what are shared derived traits?
derived trait shown ACROSS SPECIES (e.g. cloven hoof found in cows, goats, deer)
