BIO 150 - Natural Selection and Evolution

Does not have SPECIATION AND EXTINCTION

• Theory of Natural Selection; Alfred Wallace

Charles Robert Darwin (1809-1882)

• H.M.S. Beagle’s naturalist (1831-1836)

• Investigated geology

• Made natural history collections

• Galapagos Islands – west of Ecuador (S. America)

• Collected 31 birds belonging to 12 species of finches

• • Published _______________ jointly with ______________ in 1858

• Published On the Origin of Species in 1859

• Father of Evolution

__________________ - faunal divide separating Indonesian archipelago into W & E regions w/different origins

• mutation

• natural selection

• migration

• gene flow

• random changes in gene frequencies/genetic drift

THE (R)EVOLUTION OF THE THEORY

5 Evolutionary Processes:

• ___________

• ___________

• ___________

• ___________

• ___________

adaptation

________________ - the process by which a species becomes fitted to its environment; it is the result of natural selection’s acting upon heritable variation over several generations.

Abaptation

______________ - The process by which the present match between organisms and their environment, and the constraints on this match, have been determined by evolutionary forces acting on ancestors.

Abaptation

Adaptations; Abaptations

_____________ - The heritable characteristics of an organism are consequences of the past.

Present _____________ are consequences of past ______________

What is the mechanism for evolution?

Equilibrium Theory of Island Biogeography by MacArthur and Wilson (1960)

The theory states that small, protected areas isolated by modified habitats behave like “islands” and will lose some of their original species until a new equilibrium is reached, depending on the area’s size, richness & diversity, & its degree of isolation from other similar habitats.

Equilibrium Theory of Island Biogeography by MacArthur and Wilson (1960)

This theory predicts the possible number of species in an area depending on island size, distance from colonizing sources and stabilized local extinctions.

Biogeographic regions

_____________________ are results of long-term plate movements that isolated plates and brought plates together via land bridges and coalescence.

• They are considered as Earth’s biological subdivision sharing similar organisms and different from those found in other regions.

• Nearctic – N. America (U.S., Canada & parts of Mexico)

• Palearctic – Eurasia

• Ethiopian – Africa (sub-Saharan Africa)

• Australian – Australia & New Guinea

The following are the Terrestrial Biogeographic Regions including the areas comprising these regions:

• __________ – N. America (U.S., Canada & parts of Mexico)

• __________ – Eurasia

• __________ – Africa (sub-Saharan Africa)

• __________ – Australia & New Guinea

• Oriental – SE Asia

• Neotropical – C & SAmerica; most of Mexico

• Oceanian – Antarctica & Pacific Islands

The following are the Terrestrial Biogeographic Regions including the areas comprising these regions:

• __________ – SE Asia

• __________ – C & SAmerica; most of Mexico

• __________ – Antarctica & Pacific Islands

• Eastern Atlantic - Europe & W. Africa

• Western Atlantic – NE & South America

• Eastern Pacific – NW & South America

The following are the Marine Biogeographic Regions including the areas comprising these regions:

• __________ - Europe & W. Africa

• __________ – NE & South America

• __________ – NW & South America

• Indo-Western Pacific - China, SE Asia

• Indian Ocean – between E Africa & around India

The following are the Marine Biogeographic Regions including the areas comprising these regions:

• __________ - China, SE Asia

• __________ – between E Africa & around India

Artificial Selection

________________ - The selective breeding of domesticated plants and animals by man

Directional

Modes of selection

_________________ - moves the frequency towards one direction; may be positive or purifying (removal of certain alleles.)

Stabilizing

Modes of selection

_______________ - occurs when there is heterozygous advantage

Diversifying

Modes of selection

________________ - selection against the mean; extremes are favored;

EVOLUTION

The change in genetic composition of a population over many generations

Divergent Evolution

__________________

• From a common phyletic line, but evolved into different species

• Different species came about from being exposed to different environments

Adaptive Radiation

____________________

• Emergence of numerous species from a common ancestor introduced to new and diverse environments.

Convergent Evolution

_________________

• From different phyla but evolved the same characteristics

• Different species resemble each other which came about from living in similar environments

Parallel Evolution

_______________

• From same phyletic lines but separated by history

• e.g. placental & marsupial mammals

• Fossil

• biogeography

• anatomy; development

• Molecular

Data used to study evolution

• _________ records

• Historical ____________

• Comparative _________ and ___________

• ___________ data

Biological Species Concept

SPECIATION
How do species originate?

________________ - a group of morphologically similar organisms that interbreed in nature and are reproductively isolated from all other such groups

Phylogenetic

Morphological

____________________ species concept – species is an irreducible (basal) cluster of organisms that is diagnosably distinct from other such clusters

______________ species concept – based on distinctive morphological features

Why do species evolve?

Allopatric speciation (by vicariance)

Modes of Speciation

the evolution of genetic reproductive barriers between populations that are geographically separated by a physical barrier

Peripatric speciation

Modes of Speciation

occurs when a small subset of a population is isolated (becomes peripheral), and genetic drift and natural selection drive evolution of reproductive isolation between the source and founding populations

Parapatric speciation

Modes of Speciation

occurs when divergent selection is stronger than gene flow between populations in adjacent areas

limited interbreeding

Parapatric speciation

Modes of Speciation

• limited interbreeding

• ranges do not overlap but are immediately adjacent to each other (minimal contact)

Sympatric speciation

Modes of Speciation

occurs when a biological barrier to gene exchange arose within an initially randomly mating population without spatial segregation of incipient species.

Sympatric speciation

Modes of Speciation

sexual selection by females may drive __________ speciation

Sympatric speciation

Modes of Speciation

involves abrupt genetic changes that quickly leads to reproductive isolation of a group of individuals

Ex. polyploidization

Sympatric speciation

Modes of Speciation

genetic changes enable members of a species to occupy a new niche within the same geographic range

The ultimate fate of all species, just as death is for all individual organisms

• environment

• genes

• mutations; quickly

Extinction in the Context of Evolution

IF

• the _____________ changes rapidly

• the species living in these environments do not already possess __________ which enable survival in the face of such change

• random __________ do not accumulate __________ enough then,

All members of the unlucky species may die.

Genetics and Demographics

Extinction Extinction caused by humans goes as far as thousands of years ago. In the Americas, large animals became extinct around the same time as the first human presence there. It is typically caused by opening of new niches that some organisms cannot readily adapt to or by removing interspecific competition. The main causes of extinction include the following:

____________________ - Small populations increase risk of extinction Mutations can cause a flux in natural selection which overrules the expression of beneficial genetic traits. Shallow gene pools may promote massive inbreeding leading to loss of genetic diversity.

Habitat degradation

Extinction Extinction caused by humans goes as far as thousands of years ago. In the Americas, large animals became extinct around the same time as the first human presence there. It is typically caused by opening of new niches that some organisms cannot readily adapt to or by removing interspecific competition. The main causes of extinction include the following:

__________________ - It is considered one of the most influential causes of extinction. It may be due anthropogenic or natural occurrences.

Toxicity

Extinction Extinction caused by humans goes as far as thousands of years ago. In the Americas, large animals became extinct around the same time as the first human presence there. It is typically caused by opening of new niches that some organisms cannot readily adapt to or by removing interspecific competition. The main causes of extinction include the following:

___________________ - Increasing toxicity leads to increasing competition for habitat resources. Toxicity can kill off species directly through food/water & indirectly via sterilization. It can occur in a single or over several generations.

Habitat destruction

Extinction Extinction caused by humans goes as far as thousands of years ago. In the Americas, large animals became extinct around the same time as the first human presence there. It is typically caused by opening of new niches that some organisms cannot readily adapt to or by removing interspecific competition. The main causes of extinction include the following:

_____________________ - Elimination of living space can cause change in habitat such as changing rainforest to pasture lands. It leads to diminished resources and thus increasing competition. Recently, most habitat destruction is due to human causes. Natural processes such as volcanic eruption, flood and drought can also destroy habitats.

Predator introduction

Extinction Extinction caused by humans goes as far as thousands of years ago. In the Americas, large animals became extinct around the same time as the first human presence there. It is typically caused by opening of new niches that some organisms cannot readily adapt to or by removing interspecific competition. The main causes of extinction include the following:

__________________ - Invasive alien species may be transported by humans on or not on purpose. Predators can eat other species and compete with food sources. They may also introduce diseases that may prove lethal to the prey or other species they may encounter.