Macroevolution and Microevolution

Biological Evolution

statistically significant changes in the frequencies or inherited characteristics in a population over generations

Biological Species

Groups of interbreeding natural populations reproductively isolated from other groups

Two Broad categories of evolutionary change

Macroevolution and Microevolution

Macroevolution

Evolution above the single species level (E.g., genus, family, order, etc.)

Fst

Fixation Index (values range from 0-1)

Fst 0: same species, no structure

Fst 1: different species, complete structure

Fst measures…

the degree of subpopulation structure.

measures how much genetic structure there is to the overall population or differences between subpopulations within the larger population 

Fst of 0

subpopulations are not differentiated, completely interbreeding and NO GENETIC STRUCTURE

Genetic Variation

refers to genetic variation within a species

Fst of 1

two subpopulations are completely differentiated. not interbreeding and probably different species.

Genetic Divergence

fixed genetic differences between different species

Average Human Fst value is usually estimated between …

0.10-0.15

indicates small to medium genetic differentiation among human subpopulations

ESU

Evolutionary Significant Units

Why are Human Fst values not sufficient to warrant subspecies status or race names for any Human subpopulation

a) All human populations are capable of reproducing with all other populations

b) In Humans, Fst increases with increasing geographic distance from Africa

Fst correlation

Fst is positively correlated with geographic distance from Africa and shows isolation by distance where genetic differences increase with geographic distance from source

gene flow

limited by the increasing distance from the source population

Genetic Drift

due to small populations sizes and founder effects along the leading edges of an expanding population

Allele frequencies might be different in a newly founded subpopulation due to which individuals successfully…

a) left the source population

b) survived

c) reproduced

Human genetic variation has been shaped by both…

selection and genetic drift

Human genetic variation is consistent with a species that formed…

recently and rapidly dispersed over a wide geographic range

Paleoanthropology

combines paleontology and anthropology to study the early evolution and cultural development of anatomically modern humans, Homo sapiens

Anthropogenesis

or Hominization: origin and development of anatomically modern Humans

Morphological variation within a species is…

CONTINUOUS not discrete

because of all the overlap among human populations, we could identify the ancestry of a Human skull with…

a probability NOT a certainty

common patterns of mtDNA variation within a species: 1

a single most common haplotype with: 

and many small variations descended from it

common patterns of mtDNA variation within a species: 2

a single region/locality might have:

multiple different haplotypes

common patterns of mtDNA variation within a species: 3

a single haplotype could be found at many different regions/locations

common patterns of mtDNA variation within a species: 4

having a lot of genetic variation doesn’t guarantee there will be a lot of GENETIC STRUCTURE

microevolution

how allele frequencies change within/between populations

mutations

source of all genetic variation

natural selection

differential survival and reproduction among individuals based on inherited characters

sexual selection

differential mating and fertilization based on inherited characters. aka:

non random mating