Lecture 6 - Classification of Species

who is the father of taxonomy that was inspired by john ray

linnaeus

linnaeus proposed hierarchical classification of

organisms into levels

what are the classification of organism levels

class, order, genus, species

what are the three broad groups called

kingdoms

linnaeus also believed in

fixity of species

what is taxonomy?

science of defining and naming groups of organisms on the basis of SHARED CHARACTERISTICS

what is species?

group of organisms that can interbreed and produce fertile offspring

what is genus?

group of similar species

first four hierarchy of biological classification (IN ORDER)

species, genus, family, order

last three hierarchy of biological classification (IN ORDER)

class, phylum, kingdom

what is the basic unit of classification

species

what is speciation

making of a new species

speciation is a process by which

genetically distinct species arise

as adaptation and differences accumulate in speciation, organisms become so

different they can no longer interbreed

reproductive isolation may lead to

speciation

if gene pool is isolated, any mutation or selection that occurs is

no longer shared (no gene flow)

any significant evolutionary changes that occue in either population will result in

formation of a new. species (speciation)

what is gradualism?

slow accumulation of many heritable changes in a population due to small episode of natural selection

for gradualism, one species changes slowly over time until it looks so different

we call it a new species

anagenesis

unibranching

gradualism is rare compared to

branching speciation

what is branching?

type of speciation in which branching of new forms from an ancestral lineage occurs

cladogenesis

branching

for anagensis it is evolution within the lineage but for cladogenesis,

evolution due to splitting lineage

for anagensis there is no geographic barrier, but for cladogenesis

geographic barrier

example of anagenesis

horse

example of cladogenesis

darwin’s finches

what is punctuated equilibrium theory?

long periods of little to no evolutionary change punctuated by periods of rapid evolutionary change

for punctuated equilbrium theory, change mostly concentrated in

speciation events, cladogenesis

extinction and speciation are connected

true

mass extinction events often followed by

mass adaptive radiationswh

at is adaptive radiation?

diversification into different ecological niches

what is ancestral trait?

trait that evolved in a common acestor of both groups

what is derived trait?

trait that evolved in one group but not the other (a new trait)

what is a homologous structure?

shared evolutionary ancestor, similar structure but different function

what is analogous structure?

do not share a common ancestor, different structure but same function

wha tis parallel evolution?

when RELATED species evolve similar characteristics independently

what is the result of parallel evolution?

organisms that look alike and have a common acestry but live in different location

why does parallel evolution occur?

genetically related species adapt to similar environmental changes in similar ways

what is convergent evolution?

unrelated species from different locations begin to look alike because they inhabit similar environments

example of convergent evolution

tasmanian tiger and north american coyote