lesson 4 Speciation and Macroevolution

What is speciation?

the splitting of one species into two distinct species

What are diagnostic traits?

distinct physical characteristics, that define an organism

What are cryptic species?

two different species that look identical but differ in some other way

What is the evolutionary species concept?

Relies on the identification of certain morphological traits to distinguish one species from another, track evolution as specific characteristics change over time

What is phylogenic species concept?

classifying species based on evolutionary relationships rather than just physical traits, common ancestors

What is monophyletic?

A branch that contains all the descendants of a common ancestor

What is an isolating mechanism?

barriers that prevent successful reproduction

what is prezygotic isolation?

reproductive isolation mechanism that occurs before fertilization, preventing mating or fertilization between species

what is postzygotic isolation?

reproductive isolation mechanism that happens after fertilization, where hybrid offspring are produced but are often sterile or have reduced viability

example of prezygotic isolation

habitat isolation, temporal isolation, behavioral isolation

example of postzygotic isolation

zygote mortality, hybrid sterility, F2 fitness

What is allopatric speciation?

formation of a new species because of geographical isolation

What is sympatric speciation?

formation of a new species with geographical isolation but because of diverse ecological pressure

What is gradualism?

speciation that happens slowly and gradually over long periods

What is punctuated equilibrium?

proposes that species remain relatively stable for long periods, interrupted by short, rapid bursts of change

what is divergent evolution?

Type of speciation that occurs when a single ancestral species gives rise to a variety of new species as each adapts to a specific environment

example of divergent evolution

Darwin’s finches evolved into different species with unique beak shapes to exploit available food sources

what is convergent evolution?

Occurs when a biological trait evolves in two unrelated species as a result of exposure to similar environments

example of convergent evolution

Despite lacking a recent common ancestor, these species develop analogous adaptations, such as the streamlined bodies of dolphins
and sharks.

What’s a hox gene?

fundamental to the development of an organism, playing a crucial role in specifying the regions of the body plan during embryonic development. These genes essentially act as genetic blueprints that dictate where certain body structures should form, ensuring that an organism's anatomy is organized correctly