evolutonary biology

Microevolution

Occrurance of small scale changes in the gene pool at the population or species level and the mechanisms that cause these changes

Macroevolution

evolution above the species level

Natural selection

the differential reproductive sucess of its varient members

Pre darwin ideology

No acceptance for transmutation (the changing of a species over time)

John Rey

first to produce a biological defenition of species.

he developed clasifcation systems- classified according to simmilarites and diffrences that emerged from observation

carlos linnaeus

establised conventions for naming organisms

belileved that there was a system naturae

grouped together specied according to a hierarcy of increasingly general catagories.

published Syestema Naturae

did not admit to evolution

did not consider geographical variation

Georges Cuvier

palentologest- study of fossils,

documented the succession of fossil specied in the paris basin.

this helped evolutionary theory as it reperents the remains of past life that did not exist anymore showing that they have evolved

beleived that species were not immutable

catastrophism- each boudry beyween the strata represented a catastrophy

James hutton

founder of modern geoglogy

advocated the theory of Gradualism profound change is the cumulative product of slow continueous processes

the earth was shaped by slow moving forced that acted over a very long period of time

Charles lyell

integrated huttons concept into a princepal

uniformitarianism- the same forces act now that acted throughout the history of earth

the world changes in slow gradual steps building up small causes over long times to great effect.

Georg Buffon

Poposed that life forms are not fixed and that specied can change over time.

law: distinct plants and animals are found in diffrenet regions even with similar enviorments - biogeography.

Jean Baptiste Lamark

theory of eveolution comapred current speces with fosicl forms and could identify phyletic change- changes that happen gradualy throught time within a species - adaptation

did not correctly idenify the driving force behind speciation or evolution

lamarks theory

use and disuse - parts of the body that are used regularly to cope with enviormental change whilst parts that are not used deteriorate.

inheretance of acquired charateristics - the modifcation thay an organism aquires during its life can be ingerted by its offspring

problems of lamarkism

no evidence of acquired charteristics being inherited

incorrectly explained the process of speciation

changes in the scientific approach

• imperical thought

relys on observation to form an idea or hypothisis rather than trying to understand life from a non physical or spiritual pov

this shift causes scholors to look for rational behind given proceess or phenomenons

darvins history

born in 1809 shrophshire england

was studying medicine but left to study the natural world and he had a passion for it, was about to join the clergy

he mey revd henslow- proff of botany at caimbridge and was recomdened to join an expidetion on the hms beagle as the ships natrualist. the voyage was to map out unkowin parts of the south american coastline

tomas malthus

argued that only a fraction of any population including humans will survive and reproduce

Natrual selection

• more offspring produced than can survive

• competition for limmeted resources

  • individal with better traits will flourish and reproduce

ecolutionary adaptaion

a population of organims changes over the generations if indivduals having certain heritable traits leave more offspring than other individals

principals of natrual selection

darwins 4 postulates

1. indivduals in a population are variable

2. variation is passes onto the offspring

3. in every generation more offspring are produced than can survive this provides a strugle for existance

   4. the survival and reproduction of individuals is not random. indivuals with more favoravle varations will survive and reproduce at higher rates

Alfred Wallace

• collected specimens in the amazon first and in the maly archipelago

• he independently developed and almost identical theory of evolution to darwins

“The Origin of Species developed two main points:

Extant species descended from ancestral species. – It refers to evolution as the explanation for life’s unity and diversity: Descent with modification from a common ancestor

2) The mechanism driving “adaptive evolution” (i.e. environmental adaptation) is Natural Selection

mendels experiments

crossed pea plants with different traits and discoverd that parents pass discreate hertiable factors (genes) to their offspring

4 Modes of Selection that act on quantitative characters

1) Directional Selection

2) Stabilising Selection (normalising)

3) Disruptive Selection (diversifying)

4) Balancing Selection

directional selection

individuals at one extreme of a phenotypic range have a greater reproductive sucess in a particular enviorment

initators

• new allele with higher fitness introduced

  • prolonged enviormental change

stabilising selection

favors the survival of indaviduals with intermediate phenotypes extreme values of a trait are selected against

clutch size

• too many eggs and offspring die due to lack of care and food

• too few eggs dose not contribute enough to next generation

Disruptive selection

favors the survival of two ore more different genotypes that produce different phenotypes

• likley to occur in populations that occupy hetrogeneous enviorments.

balancing celection

mantains genetic diversity

balanced polymorphusm

two or more alleles are kept in ballance and therefore are mantained in a population over the course of many generations.

the ability of indaviduals to survive and reporduce has 2 components

the probablity of survival to reproductive age

the average number of offspring produced

taxonomy

the clasifcation and naming of organisms

phyogenetics

the study of the evolutionary history of a species or group of species

syestematics

clasifies organisms and determines their evolutionary relationships

homolgies

chareters that indicate shared ancestry

linnaeus syetem for grouping species

from broad to narrow- Domain,kingdom, phylum, class, order, family , genus and species

phylogeny

branching and re branching from a common ancestor symbolic of the diversity of living organisms, descent with modifcation

homology

similarties among various species that occur because they are dervived from a common ancestor

phenogram

a branching diagram that links taxa by estimates of overall similarity

phenetic clasifaction

groups animals by comparing simlartites and differences in various characteristics

cladistics

Groups organisms by common decent, identifying characteritics that indicate shared ancestry (homologus charachters)

phylogenetic clasifcation

clasifies a species according to how recently they chared a common ancestor

homology is

simmilarity due to shared ancestry

analogy is

simmilarity due to convergent evolution

convergent evolution

occurs when similar enviormental pressures and natrual selection produce similar adaptations in organisms from different evolutionary lineages

monophyletic

a clade that consist of an ancestral species and all of its desendants

paraphyletic

grouping consisits of and ancenstral species and some but not al of the desendants

polyphyletic

grouping consists of various speces with different ancestors

primitive charachter or plesiomorphy

shared by 2 or more difrenet taxa and inherited from ancestors older than their last comonn ancestor

derived character or apomprphy

shared by 2 or more speices or taxa and has orgignated in their most recent common ancestor

outgroup

a species closley related to the ingroup, the various species being studied

molecular phylogenetics

the use of the structure of molecules to gain info in an organisms evolutionary relationships

steps of molectular phylogenetics

1. choose appropriate sequence

2. allign the sequences

3. examine the sequence data for singals or patterns indcating evolutionary process

4. data analysis and phylogenetic tree building

5. test the phylogenetic reliebility of the tree estimate the support for each group

traditional classifcation based on body plan

4 main morphological and developmental features used

1. Presence or absence of different tissue types

2. Type of body symmetry

3. Presence or absence of a true body cavity

4. Patterns of embryonic development

key traits shared by land plants and algae

multicellular

eukaryotic

photosynthetic

determinate cleavage

fate of embyonic cell determined early

intermediate cleavage

individual cells from 4 cell embryo can grow independently

blatopore

region of the blastula that invaginates

can either become the mouth or the anus

pseudocoelum

body cavity is only partialy lined with mesoderm

coelomate

the body cavity is completley lined wirh mesoderm

acoelmate

lack a fluid filled body cavity

Ctenophora

produce smooth muscle, similar to bilaterians like Platyhelminthes, whereas Cnidaria have epitheliomuscular cells • The Ctenophora smooth muscle originates from the mesoderm, which the Cnidaria lac

vision

The Ctenophora have Class I vision whereas Cnidaria have Class I-III vision • The Cnidaria have the Cnidops cascade, which is unique

polymorphisms

two or more variations of given character

results in multiple alleles of the same gene

speciation

theo origin of new species, at the focal point of evolutionary theory

morphological species concept

a group of orgainsims with a specific set of morphological traits

cladogenisis

division of a species into 2 or more species

allopatric speciation

gene flow is interupted or reduced when a population is divided into geographyly isolated sub populations