BIOL 211 Lecture Notes - Lecture 11: Gamete, Species Complex, Reproductive Isolation

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28 Feb 2017

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Mechanisms of evolution: natural selection (from last time) Natural selection differential survival and reproduction of individuals in a population based on heritable variation in their phenotypes. Phenotype: observable properties of an individual (structure, color, behavior etc. : determined partially by genotype and partially by environment. If there is heritable variation in phenotype and that variation affects the survival and reproduction of individuals, then there will be changes in allele frequency. Suicide in lemmings is not an adaptation; a non-suicidal phenotype would immediatlely increase in frequency, and the non-suicidal allele would be strongly selected for. Natural selection does not favor traits that are good for the population or the species. Same with some pipefishes: sexual selection is different from normal natural selection because it may have affects counter to that of normal natural selection, which tends to favor traits that increase survival.

Related Questions

Which of the following provides evidence for evolution?

All of these answers are correct

Comparing DNA sequences between species

Looking at the geographic distribution of similar species

Analyzing transitional fossils

Which one of the following statements is true?

Natural selection works on non-heritable traits.

Mutations only give rise to harmful traits.

Natural selection works on variation already present in a population.

Individuals evolve through natural selection.

Which one of the following can create new alleles?

Which of the following is true concerning evolution?

An individual can evolve

Genetic drift is a non-random part of natural selection

An organism's fitness is determined by how long it survives

Natural selection occurs through a change in allele frequency

All living things need carbon. How does carbon enter the living portion of an ecosystem?

Atmospheric carbon dioxide taken in by photosynthesis.

Atmospheric carbon dioxide taken in by soil bacteria.

Elemental carbon taken in by plant roots.

Elemental carbon taken in by cellular respiration.

Elemental carbon taken in by cellular transpiration.

The burning of fossil fuels:

Releases excess carbon dioxide into the atmosphere.

Removes pollutants from the atmosphere.

Was developed by scientists to combat global climate change.

Has no effect on the carbon cycle.

Is good for the environment

__________ conducts water and dissolved minerals from the __________ to the ___________.

Phloem; roots; shoots

Xylem; roots; shoots

Phloem; shoots; roots

Xylem; shoots; roots

What is a disadvantage of growing traditional crops such as corn, soy or sugar cane for making biofuel?

they require lots of land and fresh water

they take carbon dioxide out of the atmosphere

they release oxygen into the atmosphere

they release water through their stomata

______ is the source of the oxygen gas released by a photosystem.

Through what structure(s) do plants obtain most of their water?

Evolution is change over ____________. Why is evolution an important concept in biology?

What is a population? How can you identify a population in nature?

What is the ultimate source of random variation in a population? Is this the only source of variation, why or why not?

What is a gene pool? Why is it important to our study of evolution?

How is variation inherited in a population? HINT: There are at least two main contributors to this variation. You should be focusing on gametes!

What is microevolution versus macroevolution?

How do the peppered moths show us microevolution in nature? Why is this NOT macroevolution? HINT: you should consider alleles and mating in your answer.

Do you believe that the Hardy-Weinberg equilibrium is common in nature? Why or why not? In your answer, you should incorporate your knowledge of populations, evolution, and genetics.

Evolution is driven by adaptation and natural selection. In populations, we refer to organisms that are âmost fit.â Explain how evolution and the environment would result in organisms that are âmost fit.â In your answer, indicate whether the âmost fitâ organism today is likely to be the âmost fitâ organism in the future and why.

Microevolution is a change in the frequency of ___________________ in a population but has not resulted in a speciation event thus far. Given this, what factors could lead to a speciation event for this population?

How would you know that a population had divided into two different species (macroevolution)? How could you test for a speciation event experimentally?

In a large population of an annual wild pea species, height is controlled by a single locus; DD and Dd individuals are tall, while dd individuals are short. Because the local environment is very windy, tall plants tend to get broken and survive to reproduce only half as well as well as do short plants. Mating is random with respect to height and there is no immigration or emigration. In a population of 21,000 (large enough to be considered infinite for the purposed of the Hardy-Weinberg equilibrium and natural selection models; assume this population size remains constant through the generations described in this question) adult pea plants that successfully reproduce after natural selection through differential survival has occurred, there are 7,000 DD individuals, 7,000 Dd individuals, and 7,000 dd individuals.

a) What will be the frequency of the D allele in the gametes (sperm, in pollen, and ovules) that will unite to make up the next generation?

b) What will be the genotype frequencies of DD, Dd, and dd in the seeds that are formed to start the next generation? How many seeds will there be with each genotype?

c) What will be the genotype frequencies of DD, Dd, and dd in the adults that develop from these seeds and survive to reproduce? How many adults will there be with each genotype?

d) Over a long period of time, what do you expect to happen to the D and d alleles in this population? Why?

BIOL 211 Lecture Notes - Lecture 11: Gamete, Species Complex, Reproductive Isolation

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