24.2 Mechanisms of Speciation

Chapter 24 deals with energy and resources.

A female mammal uses a lot of energy to produce her offspring.

America has isolating mechanisms because they don't waste a lot of energy.

3.5 mya came from the Sea Isthmus of Panama.

America Speciation, the formation of a new species, is caused by genetic changes in a particular group that make it different from the species from which it was derived.

Natural selection and evolution can change the genetics of a population.

New species often evolve in this way.

The formation of the Isthmus of Panama may have contributed to the formation of new fish species.
The underlying cause of speciation is the two populations that accumulate.
The Panamic porkfish is a unique species due to the formation of genetic changes.

Even though genetic changes account for the differences among living organisms.

The two main explanations are from the past.

Speciation may occur due to a population.

The fish is called Panamic pork 2.

The reproductive isolation is a result of that adaptation.

The formation of the Isthmus of Panama is one of the factors that may play a role.

The waters of the Pacific Ocean and the Caribbean Sea have reproductive isolating mechanisms.

The environments are critical to the process of speciation.

In the case of sexually reproducing organisms, the process and the mainland population are not very frequent.

In a relatively short period of time, the small founding population on the island may evolve two or more populations, limiting or eliminating reproduction between into a new species.
This form of speciation leads to adaptation to a new environment.
A form of genetic drift known as the evolution of one or more species occurs when a population becomes isolated from other populations.
The founder effect can have a larger influence in small founding populations.

Allopatric speciation is a showcase of the Hawaiian Islands.

A small number of founding species riers have been enabled by the islands' extreme isolation and phenomenal array of geological events.

A mountain range can split one spe into many different species.

The ancestors of the honeycreepers are believed to be related to a rosefinch that arrived on the Hawaiian Islands.

At least 54 different species of honeycreepers have evolved on the islands since that time.

Before we end our discussion of allopatric speciation, let's talk about how diversity of honeycreepers on the Hawaiian Islands was a result of diversifying selection.

There is a deer and a family of birds.

At least 54 different species of honeycreep ers, many of which are now extinct, evolved from this founding popu lation to fill available niches in the islands' habitats.

Natural selection resulted in the formation of many species.
Seed eaters can crack tough husks.
Two populations of deer are boring.
The mountain range separates the curved bil s of honeycreepers.
A mountain in Hawaii has a hybrid zone where they can extract the flowers of Hawaii's endemic plants.

Chapter 24 connects two deer populations.

The amount of gene flow within hybrid zones must become very limited for speciation to occur.

The two populations differ due to mechanical isolation.

Smaller individuals may be less likely to mate with each other in the hybrid zone due to genetic changes, as well as the ability of individuals from different popu to prefer larger individuals as mates.

Natural selection in the western deer population may be diminished, the two populations are reproductively isolated.

Increasing body size that is not favored in the eastern pop course may evolve into distinct populations.

The birds were released into the wild after being banded.

The bandaging of Darwin's finches on the Gal/apagos Islands to determine how provided a way of identifying the birds whose beaks had already been environmental adaptation may contribute to reproductive isolation.
The songs of the banded birds were recorded in honeycreepers, the beak sizes and shapes of the banded birds were recorded on a tape recorder, and the range of frequencies and trill rate of the banded birds were recorded.

The data for the Gal/apagos finches was compared to the data for a large Podos to see if changes in beak shape could affect the data collected on many other bird species.

The potential to affect comparison was used to evaluate beak size, in this case, beak mate choice, because of the songs that the birds produce.
The components of the vocal tract of birds, including the depth, work together to produce a bird's song.

The results of the comparison are shown in the data of the movements of the beak.

Podos focused on two aspects of a bird's song because of the relative constraint on vocal performance.

As the beak depth grew, the first feature became higher.
The minimum and maximum frequencies of a bird's song are measured in kilohertz, while the minimum and maximum frequencies of a trill mum are measured in kilohertz.

The second feature is the trill rate.

A trill is a group of notes that are used to crack open larger, harder seeds.
The song pat finches with smaller beaks adapted to probe for insects or eat smaller terns of these finches are quite different from each other.

The frequencies of each bird's song are measured in kilohertz.

At regular intervals, the songs are produced in a series of trills that have a particular pattern.
Different species of birds have different frequencies and trill rates.

The songs of the Galapagos finches may be affected by beak changes that are adapted for feeding.

The study was done on the finch populations of the island.

Measure the depth of the male finches' beak.

From top to bottom, beak depth is measured.

This is a measurement of beak size.

The birds should be banded and released back into the wild.

Banding can be used to identify birds with known beak depths.

This is a way to measure the variation in a song.

The trill rate is the value of the range.

The time is repeated per unit time.

The trill rate is C. pallidus G. Each bird's beak depth was analyzed.

The beak size is an adaptation to cracking open large, hard seeds.

This may affect mating song patterns and promote reproductive isolation.

Darwin's finches have a similar evolution of their vocal signal structure.

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Two diploid species are interbreeding.

It may have been the result of an interspecies cross polyploidy, adaptation to local environments, and sexual selection.

During meiosis, there is a complete nondisjunction of chromosomes.

Changes in the chromosomes can result in an abrupt monoploid for one set and a diploid for the other.
The monoploid set cannot have four sets of chromosomes from the same diploid species.
The children are expected to have two sets.
A cross between a diploid and a tetraploid produces a triploid that is sterile because it has incomplete offspring with three sets of chromosomes.
There are usu sets of chromosomes in triploid offspring.
An odd number of chromosomes can't be isolated from both diploid species, so the ally is sterile.
There was a separate area during meiosis.
The process of hybrid sterility causes reproductive fore and could lead to the creation of a new species.

Interspecies Polyploidy is a major mechanism of breeding in plants.

In flowering plants, about 40% of the mosomes come from two or more different species.
The term refers to species that are polyploid.
Polyploidy can occur in animals, but it is less common than it is in humans.
Polyploids are derived from diploid ancestors.
It is not known why polyploidy is not usually accepted in animals.

Populations have diploid offspring.

The closely related species of grasses that occupy different local environments may interbreed to produce allodiploids.
Different species may be formed by an organisms containing each other.
An example of two or more complete sets of chromosomes is called an allopolyploid.
Jeffrey Feder, Guy Bush, and colleagues can be an allopolyploid.
The fly origi polyploid can occur as a result of nondisjunction in an allo nally fed on native hawthorn trees.
A new local envi allodiploid could produce an allopoly ronment, which is an allopoly ronment for this species, if the complete nondisjunction in an apple tree had existed 200 years ago.
The apple-feeding populations of this spe ploid with two complete sets of chromosomes from two species develop more rapidly than the total of four sets.

A subsequent nondisjunction event may have arisen from an interspecies cross between the two species.

Polyploidy may have led to reproductive isolation between the three natural species.
The resulting offspring will be sterile if G. tetrahit is crossed with either of the other two species.
It is a new species because it is reproductively isolated from the diploid species.

If G. tetrahit was crossed to G. pubescens, there would be an interspecies hybrid.

You should give a range, not a single number.

The two differences are highly specialized.

Pea aphids found on red hawthorn trees exhibit a lower fit than those found on apple trees, and evolutionary biologists theorize they may eventually become distinct species.
Host ductive isolation and the accumulation of independent mutations have the same characteristics.

This may be an important mechanism of sympat on these two plants, they show significant genetic ric speciation among insects.