BIOLOGY NOW: Adaptation and Speciation (Chapter 13)

Flashcards covering key concepts from Chapter 13: Adaptation and Speciation, including adaptive traits, biological fitness, species concepts, speciation types, and reproductive barriers.

What is biological fitness?

Survival and successful reproduction of an individual.

What do adaptive traits lead to?

Higher biological fitness, enabling a species to survive and reproduce in its unique environment.

What is adaptation in a biological context?

A trait that is advantageous to an individual or a population, or the evolutionary process of natural selection that enables a good match between an organism and its environment.

How might a salt gland serve as an adaptation for an aquatic bird like a penguin?

A salt gland removes excess salt from the body, which is crucial for aquatic birds that consume saltwater prey or live in marine environments.

Why are heavy bones an adaptation for penguins but not for most other bird species?

Heavy bones help penguins reduce buoyancy, aiding in diving and underwater swimming, while most bird species require lightweight, hollow bones for flight.

According to the biological species concept, what is a species?

A group of natural populations that can interbreed to produce fertile offspring and cannot breed with other such groups.

For which types of populations does the biological species concept not work well in determining relationships?

The biological species concept does not work well for species that reproduce asexually or for extinct species (fossils) where interbreeding cannot be observed.

In addition to reproductive isolation, what three kinds of information do scientists use to identify and distinguish between species?

Scientists use biogeographic information, DNA sequence similarity, and morphology (physical characteristics).

What is speciation?

The process by which one species splits to form two or more new species.

What is genetic divergence?

The accumulation of differences in the DNA sequences of genes in two or more populations of organisms over time, resulting in genetic dissimilarity.

What is geographic isolation?

The physical separation between populations, often caused by a newly formed barrier like a river, canyon, or mountain chain, leading to little or no gene flow.

What is allopatric speciation?

The formation of new species from geographically isolated populations.

What factor must be present for allopatric speciation to occur?

Geographic isolation must be present for allopatric speciation to occur.

If two geographically separated populations reunite and interbreed, what attribute must their offspring have for the populations to still be considered the same species according to the biological species concept?

The offspring must be fertile and capable of reproducing themselves.

What is coevolution?

When two species so strongly rely on each other for survival that they evolve in tandem, with an adaptation in one species evolving alongside a complementary adaptation in another.

What is ecological isolation?

The idea that two closely-related species in the same area are reproductively isolated by minor differences in habitat or resource use.

What is sympatric speciation?

The formation of new species in the absence of geographic isolation.

What is the main difference between allopatric and sympatric speciation?

Allopatric speciation occurs with geographic isolation, while sympatric speciation occurs without it.

What two events must happen for both allopatric and sympatric speciation to occur?

Genetic divergence and reproductive isolation are two events necessary for both allopatric and sympatric speciation.

What is a reproductive barrier?

A mechanism that exists between two species when they are prevented from reproducing with each other, divided into prezygotic and postzygotic categories.

What are prezygotic barriers?

Reproductive barriers that prevent a male gamete and a female gamete from fusing to form a zygote (i.e., they act before the zygote exists).

How is the blue-footed booby's ritual dance a prezygotic reproductive barrier?

It's a behavioral isolation mechanism where distinct courtship displays prevent successful mating between different species, thereby inhibiting zygote formation.

What are some other prezygotic reproductive barriers besides a mating dance?

Ecological isolation (different habitats or breeding times), mechanical isolation (physical inability to mate), and gametic isolation (gametes cannot fuse or survive).

What are postzygotic barriers?

Reproductive barriers that prevent zygotes from developing into fertile offspring (i.e., they act after the zygote is formed).

Why is a mule (the sterile offspring of a female horse and a male donkey) an example of a postzygotic barrier?

A mule is an infertile hybrid, meaning that even if mating and fertilization occur, the resulting offspring cannot reproduce, thus preventing gene flow between horses and donkeys and maintaining their species boundaries.

The relationship between a species of ant and Acacia trees, where ants protect the tree and the tree provides hollow thorns for nests, is an example of what evolutionary process?

Coevolution, as both species have evolved complementary adaptations due to their strong reliance on each other.

Horses and donkeys can reproduce to have viable, but sterile, offspring (mules). What barrier to reproduction is happening here?

Hybrid sterility, which is a postzygotic barrier.

Which of the following is most unlikely to result in genetic divergence: ecological isolation, geographic isolation, gene flow, or a reproductive barrier?

Gene flow is most unlikely to result in genetic divergence because it involves the movement of genetic material between populations, which tends to reduce differences.