Formation of new species

Species

• a group of organisms that closely resemble each other

Population

• is a group of individuals of the same species occupying a particular habitat

What causes variations in individuals in a species

• sexual reproduction and mutations

Sexual reproduction and mutations

• Mutations in DNA which are sudden unexpected changes in genetic structure or DNA therefore producing new genes

• Meiosis in gamete formation through crossing over and random arrangement of homologous chromosome pairs

What are the effects of inbreeding and outbreeding in a population

• inbreeding is the mating of genetically closely related individuals

In nature inbreeding in population:

• leads to a loss of genetic diversity

• results in homozygosity AKA inbreeding depression

• animals have a lower birth weight

• plants produce less seeds

Outbreeding:

• leads to an increase of genetic variation

• promotes heterozygosity therefore decreases chances of offspring being affected by recessive traits

• new desirable traits are introduced

Founder effect

• refers to the loss of genetic variation when a minimal number of individuals from a larger population establish a new colony

Cheetah ( founder’s effect example)

• has low genetic diversity

• this results in poor sperm quality, low fecundity, high cub mortality and sensitivity to diseases

Convergent and Divergent evolution

• convergent: species that are not closely related evolve similar kinds of traits to adapt to similar environments or ecological niches

• divergent: the process in which a trait held by a common ancestor evolves into different variations over time such as a vertebrae limb

What is speciation

• is the evolutionary formation of new species that are genetically distinct from parental species

Geographic speciation

• due to a part of the population being geographically isolated from ancestral species

• examples: when lakes dry, seeds disperse, sea currents washing organisms

How does geographical speciation occur

• species become separated by a geographical barrier then the population splits into two

• no gene flow between the populations

• natural selection occurs independantly due to change of environment

Sympatric speciation

• is when a new species arises in the same area as the ancestral species

• plants can develop the new species

Galapagos finches’s different species arising?

• an absence of pre-existing predators

• no competition from other landbirds

• a variety of empty ecological niches

they feed on different plants and foods and were before divided by ecological climates

Mechanisms for reproductive isolation

1. Breeding at different times of the year

• prevents mating opportunities between species which are alike but are not the same

2. Species specific courtship behaviour

• it is an animal signal of sexual readiness

• breeding display

• songs by males

• secretion of pheromones

• breeding plumage

Adaptation by plants to different pollinators

• plants and their flowers have pollinator syndromes that are adapted for specific pollinators

• the flower is designed so that only one specific pollinator can get to the pollen