Evolutionary Biology: Finch Speciation and Sympatric Speciation

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Questions and Answers

What did Ernst Mayr study?

Birds of Melanesia (correct)

Tigers and lions

Fish in Lake Victoria

Mules and donkeys

What is the species concept according to Ernst Mayr?

Tigers and lions coexisting as species

Animals with different coloration in Lake Victoria

Hybrids between different species

Populations of interbreeding organisms that are reproductively isolated from other groups (correct)

What does the existence of tigons and ligers imply for species definition?

The existence of hybrids that work well

The need to produce non-sterile offspring (correct)

The perfect isolation between species

The existence of sterile hybrids

Who came up with the species concept?

Ernst Mayr Signup and view all the answers

What is the isolating mechanism according to Dobzhansky?

Mechanism leading to the evolution of reproductive isolation between groups Signup and view all the answers

What did the experiment in Lake Victoria involve?

Mate choice in two closely related fish species under colored and white light Signup and view all the answers

What was the result of the mate choice experiment conducted on two closely related fish species in lake Victoria?

Females could not tell the difference in coloration between the two species in colored light. Signup and view all the answers

What can be inferred about the hatching rates of hybrids from two butterfly species?

F1 generation hybrids are sterile, while hybrids with a male and female are normal butterflies. Signup and view all the answers

What is the primary reason for the reduced growth rate of backcross species in the wild?

Ecological dependence rather than genetic factors. Signup and view all the answers

According to the text, which type of speciation mainly involves a single population becoming two due to some barrier, leading to the creation of two gene pools?

Allopatric speciation Signup and view all the answers

What effect does range overlap have on sympatric speciation according to the text?

Range overlap decreases sympatric speciation. Signup and view all the answers

What is indicated as a significant factor promoting speciation according to the information provided?

Geographic barriers such as isthmus Signup and view all the answers

What does the variation in number of species in islands suggest according to the text?

Speciation is easier on larger islands. Signup and view all the answers

What is an example of sympatric speciation mentioned in the text?

Different species of fly have become differentiated within the same fruit tree. Signup and view all the answers

What is the best example of sympatric speciation provided in the text?

Different species of fly differentiated within the same fruit tree. Signup and view all the answers

In which scenario does reinforcement occur according to the text?

Hybrid species having reduced fitness and selection favoring parents who don’t mate with other species. Signup and view all the answers

What is the reason for the brown color of male pied fly catchers in sympatric areas?

To avoid being mistaken for a different species by females Signup and view all the answers

What is an example of allopatric divergence mentioned in the text?

Two different migratory routes of greenish warblers around the Tibetan plateau. Signup and view all the answers

What is the consequence of choosing mates with the wrong species, as mentioned in the text?

Reduced hatching rates of offspring Signup and view all the answers

What role does geographic isolation play in ring species according to the text?

It connects two populations that do not interbreed but are connected by a geographic ring of populations that can interbreed. Signup and view all the answers

What is the outcome of female hybrid fertility in the context of mate selection?

Reduced fertility in female hybrids Signup and view all the answers

What is an example of a by-product mechanism mentioned in the text?

Morphological differences between fish in high and low predation environments due to selection through predation. Signup and view all the answers

Why are F1 hybrids of fly catchers infertile?

As a result of selection against making choices across species Signup and view all the answers

What is a characteristic of reinforcement mentioned in the text?

Selection against making mistakes in mating leading to reduced number of grandchildren. Signup and view all the answers

What is the reason behind reduced choices between species in sticklebacks?

Reduced fitness incurred by hybrids Signup and view all the answers

What is indicated by the development of increasing genetic divergence of birds within the same area?

Allopatric divergence due to different migratory routes around geographical barriers. Signup and view all the answers

Why do female sticklebacks from benthic populations exhibit selection against choosing opposite species?

To avoid producing infertile offspring Signup and view all the answers

What causes reproductive isolation to build in allopatry according to the text?

The by-product mechanism associated with adaptation to alternative environments. Signup and view all the answers

What contributes to the differentiation between pied fly catcher males residing in allopatry and sympatry?

Exaggeration of differences between males in sympatry Signup and view all the answers

What leads to different species being recognized by birds despite being close but not interbreeding?

The expanded ways birds have recognized each other based on their unique songs. Signup and view all the answers

What leads to changes in mate choice and reproduction in fly catchers?

Mating with wrong species and subsequent infertility Signup and view all the answers

What occurs due to hybrid species having reduced fitness and selection favoring parents who don’t mate with other species?

The development of increasing genetic divergence of birds within the same area. Signup and view all the answers

What is the impact of mixed high-altitude habitat on fly catcher offspring?

Reduced hatching rates of offspring Signup and view all the answers

What is the result of selection for not making mistakes in mate selection?

Selection against mates with wrong species Signup and view all the answers

Study Notes

Ernst Mayr's Studies

Studied evolutionary biology and the concept of species.
Contributed to defining the biological species concept.

Species Concept According to Ernst Mayr

Defines species based on reproductive isolation; groups that can interbreed within their population.

Existence of Tigons and Ligers

Tigons and ligers imply that species definitions can be flexible; these hybrids show that interbreeding can occur between closely related species, challenging strict categorizations.

Origin of the Species Concept

The biological species concept was formulated by Ernst Mayr.

Isolating Mechanism According to Dobzhansky

Emphasizes genetic and behavioral barriers that prevent species from interbreeding, facilitating the maintenance of distinct gene pools.

Experiment in Lake Victoria

Involved mate choice among two closely related fish species, exploring preferences that inform speciation dynamics.

Result of Mate Choice Experiment

Demonstrated evidence of selective mating, influencing reproductive isolation and divergence between the two fish species.

Hatching Rates of Butterfly Hybrids

Infer that hatching rates are lower for hybrids, which indicates struggles in reproductive viability between species.

Reduced Growth Rate of Backcross Species

The primary reason for reduced growth rates is the hybrid's compromised genetic makeup affecting adaptability in wild environments.

Type of Speciation Involving Barriers

Allopatric speciation occurs when a single population is divided by barriers, leading to the emergence of two separate gene pools.

Effect of Range Overlap on Sympatric Speciation

Range overlap is crucial for sympatric speciation, promoting diversification without geographical separation.

Significant Factor Promoting Speciation

Variation in ecological niches is indicated as a significant factor that fosters speciation.

Variation in Species Numbers on Islands

Suggests that island ecosystems are influenced by isolation and environmental factors affecting species diversity.

Example of Sympatric Speciation

Cichlid fish in Lake Victoria exemplify sympatric speciation through adaptive radiation in varied habitats.

Best Example of Sympatric Speciation

The diversification of cichlids in Lake Victoria serves as an ideal representation of sympatric speciation mechanisms.

Occurrence of Reinforcement

Reinforcement occurs when selection pressure favors traits that prevent hybrid mating between similar species.

Brown Color of Male Pied Flycatchers

The brown coloration in sympatric areas serves as a selection mechanism for mates, enhancing reproductive isolation.

Example of Allopatric Divergence

An example includes the divergence of species in separate geographical locations leading to distinct adaptations.

Consequence of Wrong Mating Choices

Choosing mates of the incorrect species leads to decreased reproductive success and increased hybridization problems.

Geographic Isolation in Ring Species

Geographic isolation is essential in ring species as it allows gradual divergence between populations around a geographical barrier.

Female Hybrid Fertility Outcomes

Female hybrids often face reduced fertility, further influencing mate selection and reproductive success.

By-Product Mechanism Example

An example points to the selection pressures related to appearance and mating behaviors that inadvertently promote speciation.

Infertility of F1 Hybrids in Flycatchers

Infertility arises from genetic incompatibilities between the parental species.

Characteristic of Reinforcement

Reinforcement leads to the increased fixation of traits that enhance discrimination against hybrids.

Reduced Choices in Sticklebacks

Limited mate choices in sticklebacks are driven by environmental pressures and the avoidance of hybridization.

Genetic Divergence in Birds

Increasing genetic divergence within the same area signals the gradual process of speciation even amid ranges.

Female Sticklebacks Selection Behavior

Benthic population females exhibit preferences that discourage interbreeding with alternative species, promoting speciation.

Reproductive Isolation in Allopatry

Reproductive isolation strengthens through genetic divergence and environmental adaptation when populations are geographically isolated.

Differentiation in Pied Flycatcher Males

Differences between allopatric and sympatric pied flycatcher males arise from selective pressures influencing coloration and mating behavior.

Recognition of Close, Non-Interbreeding Species

Distinct species recognition despite geographical proximity is driven by evolved mating signals and behavioral adaptations.

Changes in Mate Choice in Flycatchers

Evolutionary pressures result in shifts in mate preference and reproductive strategies within flycatcher populations.

Consequences of Reduced Fitness in Hybrid Species

Hybrid species exhibit diminished fitness, favoring selective pressures that promote mating among similar species over hybrids.

Impact of High-Altitude Habitats on Offspring

Mixed high-altitude habitats can adversely affect flycatcher offspring, reducing survival and reproductive success.

Result of Selection Against Mistakes in Mate Selection

Selection for accurate mate choice enhances reproductive success and contributes to the stability of species boundaries.

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Description

This quiz covers the process of finch speciation, the role of allopatry, and exceptions such as sympatric speciation. It also explores the example of finches shifting from hawthorns to apples and the resulting differentiation of fly species.