WEEK 18 - phylogenetics + population genetics

2 components of binomial nomenclature

genus name, species name

what is taxonomy

classification of organisms based on shared characteristics

what do phylogenetic trees show

the evolutionary history and relatedness of organisms

what is a taxon

any group of species we designate or name (vertebrates)

what is a clade

a taxon that consists of all the descendants of a common ancestor - including the common ancestor

what is a monophyletic group

a clade - all descendants and the common ancestor

what is a paraphyletic group

a group with a common ancestor, but not all the descendants

what is a polyphyletic group

a monophyletic group excluding its common ancestor

what is the biological species concept

groups of interbreeding natural populations that are reproductively isolated from other groups

what does the BSC not apply to

allopatric species, parthenogenic species, fossil species

what is the evolutionary species concept

a single lineage of ancestor-descendant populations which maintains its identity from other lineages, which has its own evolutionary tendencies and historical fate

what is the phylogenetic species concept

recognises the distinction between species is from evolutionary change

the smallest set of organisms that share a common ancestral population and can be distinguished from other sets

how are Trees constructed

morphology - forms, shapes, structures

palaeontology - fossils give info of morphology and location

development - similarities in development pattern may reveal evolutionary relationship

behaviour - can be inherited/culturally transmitted

molecular data - DNA + amino acid sequencing

what are homologous features

features shared by 2 or more species that are inherited from a common ancestor

what is plesiomorphy

a trait present in the ancestor of a group

what is a derived trait

a trait found in a descendant that differs from ancestor

what is a synapomorphy

derived traits that are shared across a group and viewed as evidence of common ancestry

what is homoplasy

similar traits develop in unrelated groups of organisms due to convergent evolution

what is a phenotype

observable characteristics of individuals determined by genotype

what is genetic drift

chance events determine which alleles are passed onto next generation

effects of genetic drift

1. allele frequencies fluctuate randomly, disappear or fixate

2. alleles are lost - less genetic variation

3. frequency of deleterious alleles can increase, overruling natural selection

   1. differences between populations can increase

what is gene flow

alleles are transferred from one population to another by movement of individuals or gametes

2 effects of gene flow

populations become more similar

new alleles can be introduced into a population

what is a population

a group of organisms of the same species that can actually or potentially interbreed living within a prescribed area in time and space

what can the Hardy-Weinberg equation do

predict allele frequencies in a population

suggest evolution is occuring

6 assumptions for Hardy-Weinberg

random mating

allele frequencies same between M/F

genotypes equal in survival and fertility (no natural selection)

no mutation

no migration

large population size

what can genetic drift cause in smaller populations

population bottlenecks - alleles are overrepresented in the new population

founder effects - population isolation means new gene pool is not representative

what is inbreeding depression vs outbreeding depression

inbreeding depression - reduced fitness due to inbreeding

outbreeding depression - favourable gene combinations can be lost