Lecture 5 and 6 Species and Speciation

What is a species concept?

It is a way we can define species in multiple ways

What are the three types of species concept?

Morphological, genetic, and biological

What is the morphological species concept?

Organisms that differ in morphology are different species

What is the benefit of studying morphological species concept?

shows extinct animals shape/appearance and is used in paleontology

What are some limitations of morphological species concept?

It cannot be applied to microorganisms and can be misleading like men and women can look very different but be the same species

What is genetic species concept?

It sequences DNA and compare them

What are the benefits of genetic species concept?

used to determine microorganisms and if a organisms gender is the same species or not

What are the limitations of genetic species concept?

It cannot work with extinct animals, the cost, and the rest of the DNA sequence

What is the biological species concept?

A group of interbreeding natural population that are reproductively isolated from other groups

What are the benefits of biological species concepts?

It is easiest to do and it can be tested

What are the limitations of biological species concept?

Doesn’t apply to asexual species, extinct animals, and species that can be hard to observe

What is reproductive isolation?

When animals are prevented from mating due to reproductive barriers

What are the two types of reproductive isolation?

Prezygotic and postzygotic barriers?

What is a prezygotic barrier?

It is when barriers occur before fertilization

What are the three types of prezygotic barriers?

Behavioral, mechanical, and gametic isolation

What is behavioral isolation?

It is when a characteristic is not present in one species so the other species will not mate due to the lack of the trait

What is mechanical isolation?

It is when reproductive organs don’t fit

What is gametic isolation?

When sperm eggs do not combine it is incompatible.

What is a postzygotic barrier?

It happens after fertilization

What are the three types of postzygotic barriers?

reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown

What is reduced hybrid viability?

It is when a female takes sperm without knowing where it came from and will result in a hybrid offspring that will not survive long

What is reduced hybrid fertility?

When animals are in captivity and will be forced to mate and results in infertile hybrids forming

What is speciation?

A branching point where two new species are created

What are the two types of speciation?

allopatric and sympatric speciation

What is allopatric speciation?

The formation of species in physically different locations

What is a sympatric speciation?

The formation of species in the same location

Where can allopatric speciation occur?

It occurs when barriers are split and occurs as time increases

What are the steps that occur for allopatric speciation?

fusion → stability → reinforcement

When does sympatric speciation occur?

When species lay eggs or by timing

What is a hybrid zone?

if two species have incomplete reproductive barriers

What would occur if two species meet with incomplete reproductive barriers?

Species would arrive in the hybrid zone and mate

Which model completes speciation?

It would be reinforcement as it would strengthen reproductive isolation so hybridization no longer occurs