Bios 3300 Exam 3

What is the evolutionary definition of altruism?

An action in which the actor is harmed and the recipient benefits

What is the evolutionary definition of Cooperation?

An action in which both the actor and the recipient benefits

What is the evolutionary definition of Selfishness?

An action in which the actor benefits and the recipient is harmed

What is the evolutionary definition of Spite?

An action in which both the actor and the recipient are harmed

Why is altruism a problem for natural selection?

It actively harms the actor which eliminates it from the gene pool, Darwin suggested that natural selection favored altruism if the behavior benefited close relatives

What is inclusive fitness? What are the direct and indirect components of inclusive fitness?

Inclusive fitness is the sum of direct and indirect fitness on an individual. Direct fitness being personal reproduction and indirect fitness being the reproduction by relatives made possible by the individual's actions.

What is kin selection?

Natural selection favoring the spread of alleles that increase direct fitness

Know Hamilton's Rule. What are B, r, and C?

The calculation of inclusive fitness defined as Br>C, with B being the benefit to the recipient, r being the relatedness, and C being the cost to the actor

What is the coefficient of relatedness to a parent? A sibling? A cousin?

To a parent it is 1/2, to a sibling it is ¼, and to a cousin it is 1/8.

Why are nest helping in birds and alarm calls in small mammals both examples of kin selection increasing inclusive fitness?

In both cases the animals are decreasing their own direct fitness to increase the fitness of their kin

Why is whistling for hawks an example of selfishness in Belding's ground squirrels?

The whistling squirrels decreased the fitness of their counterparts and in turn increased their own direct fitness by decreasing competition

Why do North American red squirrels sometimes adopt abandoned offspring, and sometimes not?

If the squirrel is directly related to the abandoned offspring, they will adopt it and in the process decrease the survivorship of their own offspring. Without any relatedness they will not risk their own offspring's survivorship

What three characteristics are typical of eusociality?

1. Overlapping generations between parents and offspring
2. Cooperative brood care
3. Specialized casts of non-reproductive individuals

What are examples of eusocial species? Are mammals ever eusocial?

Bees, wasps, ants, and even mammals like naked mole rats

What is reciprocal altruism?

Cooperation amounts non-kin species in nature, individuals can be selected to dispense altruistic acts if equally valuable favors are later returned by the benefactor.

What two conditions need to be met for reciprocal altruism to evolve?

The cost to the actor must be less than or equal to the benefit to the recipient and cheaters must be punished

What was the example of reciprocal altruism given in class?

Blood sharing in vampire bats occurs because adults bats share meals with unlucky young bats because adult bats did the same when they were young

What is sexual dimorphism?

A difference between the phenotypes of females and males within a population

Compare and contrast natural selection and sexual selection

Natural selection is the difference between the survival or reproduction of individuals with different phenotypes usually related to components of fitness while sexual selection is the difference among members of the same sex between the mating success of individuals of different phenotypes, a special kind of natural selection.

In what ways do females and males differ in reproductive investment?

Male reproduction is limited by access to female eggs and females are limited by the number of eggs they can nurture and rear to maturity.

What is Bateman's principle?

The theory that when one sex invests more resources into producing offspring, this sex will be a limiting resource over which the other sex will compete.

What is Bateman's gradient? What are the axes in the graphs?

The slope of the best-fit line relating reproductive output to mating opportunities with the x-axis representing number of mates and the y-axis representing number of offspring

Members of the sex subject to strong sexual selection will ________________ for mates.

Compete

Members of the sex subject to weak sexual selection will be __________________.

Choosy

Are females always the choosier sex?

No, seahorses are a famous example of males being the choosier sex

What is intrasexual selection? What are the forms it takes?

Competition between members of the same sex for mates, male-male competition is the most common form.

Why do male lions commonly commit infanticide?

Female lions return to breeding condition on average 8 months sooner when infanticide is committed.

What is intersexual selection?

Intersexual selection is competition of one sec for members of another, most commonly seen in female choice

What is the good genes model of female choice? How does one test the good genes model?

Certain traits indicate that the bearer has good genes, these indicator traits tell mates that their offspring will have better genes, an example of this is female attraction to males with complimentary immune systems.

What is sensory bias? How does one test for sensory bias?

Sensory bias taking advantage of the female sensory system to trick their choice.

What is Chase-away sexual selection? How was this tested for using Drosophila?

Chase-away sexual selection is the evolutionary arms race of males evolving to increase their reproductive success and females evolving counter evolutions

What is parthenogenesis?

A natural form of asexual reproduction in which growth and development of embryos occur in a gamete without combining with another gamete; development of an embryo from an unfertilized egg

What is facultative parthenogenesis?

The ability of sexually reproducing species to sometimes produce offspring asexually

What is the two-fold cost of sex?

asexual females can produce twice as many viable female offspring as sexual females

How much of their DNA do parthenogenetic individuals pass on?

All of it deleterous mutations and all

What is Muller's ratchet? How does sex break Muller's ratchet?

Muller's ratchet is the principal that small asexual populations are doomed to accumulate ever-increasing deleterious mutation, sex breaks muller's ratchet through recombination allowing a population to purge deleterious alleles.

What is the Red Queen hypothesis?

The idea that species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species; genetic arms race.

What is genetic load?

The decrease in fitness of the average individual in a population relative to the fitness genotype due to the presence of deleterious alleles in a gene pool.

What is a thermal performance curve?

Curves used to describe how ambient temperature impacts different attributes of ectothermic organisms

What is life history?

An individual's pattern of allocation, throughout life, of time and energy to various fundamental activities such as growth, body repair, metabolism, and reproduction

What is lifetime reproductive success?

The number of offspring produced by an individual in their lifetime.

What is the life history of the ideal organism? What is meant by "allocation" in life history theory?

The ideal organism is mature at birth, continuously produces many offspring that are large, and lives forever

What is senescence?

A decline with age in reproductive performance, physiological function, or probability of survival; reduces an individual's fitness

Can longevity evolve?

Yes

Understand the mutation accumulation hypothesis for senescence

Mutations that impact fitness late in life are under weak selection so they remain in a population more compared to mutations that impact fitness early in life

Understand the antagonistic pleiotropy hypothesis for senescence

Mutations conferring fitness benefits early in life and fitness costs late in life will be under positive selection when the benefits outweigh the costs

At what rate are neutral mutations expected to accumulate in a population?

The rate of accumulation of neutral mutations = the mutation rate

Understand the mainland/island comparison of senescence in opossums

Populations with lower rates of ecological mortality (predation, parasites, etc) should evolve delayed senescence. In opossums, a population on an island was less likely to die so senescence occurred later in life compared to mainland opossums under constant threat of death.

What is the trade-off between offspring size and number? How is this calculated?

There is a tradeoff between egg mass and egg number as well as a tradeoff between egg mass and egg survival. The optimal solution for offspring size = number of offspring * expected survival

In the study of Chinook salmon, do hatcheries select for large or small eggs?

They go down the middle and select for the average sized egg to maximize both the fitness of maternal salmon and offspring.

What is the impact of hatchery fish on natural populations?

Hatchery fish have a smaller average egg than nature so natural populations close to hatcheries have had their average egg sizes decreased due to gene flow from the hatcheries.

What is Lack's hypothesis for the optimal number of offspring? How is the optimum clutch size calculated?

Lack's hypothesis is that natural selection will favor the clutch size that maximizes the number of surviving offspring. Its calculated as clutch size * probability of survival of individual offspring (CS*p)

biological species concept (BSC),

Species are groups of actual or potential interbreeding natural populations that are reproductively isolated from other such groups.
Advantages: easy and clear, can diagnose species that look the same, applicable to many ecological studies
Problems: doesn't apply to asexual species or fossils, also hybridization and allopatry are common

morphological species concept,

A group of individuals that are morphologically distinct from other groups
Advantages: works on fossils, easily identify species, doesn't require geographic overlap
Problems: geographic variation, lack of variation (cryptic species (look the same)), polymorphism within populations

phylogenetic species concept

The smallest diagnosable cluster of individuals within which there is a parental pattern of ancestry and descent
Advantages: works on cryptic species, fossils, and asexual species, broadly applicable, takes advantage of DNA sequencing
Problems: doesn't address mechanism that produces clades, is unclear about level of divergence needed, and unclear about what character to categorize with (DNA vs morphology vs molecules)

evolutionary species concept,

Species are evolutionary lineages
Advantages: separates the concept of what a species is from the criteria used to diagnose lineages, applies to fossils and asexual species
Problems: what criteria are appropriate for lineage diagnosis? what creates lineages? If a rat swam to an island is that a species?

general lineage concept (GLC)

Species are segments of separately evolving metapopulations-level lineages (evolutionary species concept rephrased)
Advantages: a series effort at unification (we all win), Darwinian view of what species are; speciation does not require special circumstances or necessary criteria
Problems: same as the evolutionary species concept

What is a cryptic species?

Two or more taxa grounded under a single name because they are morphologically identical; they look the same.

Why is the General Lineage Concept (GLC) often referred to as "unifying" within the species concept debate?

It makes the case that most of the concepts are based on the concept of species as evolutionary lineages and only differ on the criteria of organization.

Understand why the GLC considers many of the other "concepts" not to be concepts at all, but criteria for diagnosing lineages

All have value in different situations so its best to stop arguing over which is best in all situations

What is a lineage, and why does the GLC refer to species as 'segments' of lineages? How do populations relate to lineages?

A lineage is lateral descent form an ancestor so individual species are segments of this greater lineage following an altered path, in the same way populations are a mere time-slice of a lineage.

What is a species tree?

A phylogenetic tree showing the branching lineages of a species

What is a gene tree?

A component of a species tree dealing with the descent of specific allele frequencies

allopatric speciation

The evolution of distinct species when populations are geographically separated by an extrinsic barrier (vicariance and dispersal)

parapatric speciation

The evolution of separate species that are continuously distributed, but non-overlapping, in space

sympatric speciation.

The evolution of separate species within a shared geographic range

Compare and contrast vicariance and dispersal.

Vicariance is the separation of two populations by a physical barrier such as a mountain while dispersal is the natural migration of a species to a new geographical area such as islands

What is an ecotone?

A transition between two adjacent but different patches of landscape such as forest and grassland

Which mode of speciation is also called "divergence with gene flow"?

Parapatric speciation

What is the central challenge of parapatric (and also sympatric) speciation?

Natural selection must overpower gene flow along the border where the ranges meet

Which mode of speciation may be of importance for speciation in insects that are tied to particular plant species?

Sympatric speciation

What is a reproductive isolating mechanism?

Factors that cause individuals from different groups to either fail to mate, or fail to produce viable offspring

prezygotic isolation

also called pre-mating isolation (behavioral or mechanical), it is reproductive isolation between populations due to factors that prevent mating or formation of a zygote

postzygotic isolation?

Mating may occur, but the zygote does not develop properly or the offspring are not viable

Why is a mule not a species?

While it is a viable offspring of two separate species it itself cannot produce viable offspring so it can't make more mules.

In general, is there natural selection for speciation? What is the one instance in which natural selection may directly promote speciation?

In general speciation is a bye product of natural selection, it is fundamental to sympatric and parapatric speciation and natural selection of allopatric speciation is the most common mode of species formation

What is ecological speciation?

Barriers to gene flow evolve among populations as a result of ecologically-based divergent natural selection

How does parallel speciation in sticklebacks work?

Parallel speciation is when traits that determine reproductive isolation evolve independently in different populations, in sticklebacks this means that two different species that have evolved benthic morphs independently can procreate with each other.

What is Reinforcement? What is reproductive character displacement?

Process of speciation in which natural selection increases reproductive isolation, in saying that reproductive character displacement is a form of reinforcement in which traits evolve to lessen sexual interactions between species

What were identified as the 3 principals of biogeography?

Allopatric speciation, evolution, and extinction

Compare and contrast historical and ecological biogeography.

Historical biogeography is the study of the historical circumstances that contributed to the distribution of taxa while ecological biogeography is the study of the ecological circumstances that contribute to the distribution of taxa.

What are some biogeographic questions that we might ask for each type of biogeography?

For historical we might ask where did species originate? Or when did species colonize their present distributions? While for ecological we might as how do tropics differ in climate, primary productivity? Or species interactions differ in the tropics?

What does "endemic" mean?

Of a taxon, restricted to a certain region or locality

Understand Darwin's evidence for evolution from the field of biogeography, including his evidence from islands.

- Most island species were closlely related to mainland species
- these species were populated by species capable of long distance travel
- these island species bore marks of mainland ancestory.

What four historical factors impact current distributions of taxa?

1. Extinction
2. Range shifts
3. Dispersal
4. Vicariance

What are oceanic and continental islands? Why do oceanic islands have more endemic species?

Oceanic islands were never connected to the mainland while continental islands once were, because of this oceanic islands have more endemic species because mainland species couldn't readily travel to them.

What is Wallace's line?

An imaginary line between the island of the south pacific

What is Gondwanaland?

The southern half of the pangea supercontinent containing Africa, South America, Antarctica, Madagascar, and India

Explain the biogeographic history of the marsupials, and how fossils have helped us understand this history

Marsupials evolved in South America before dispersing across Gondwanaland and eventually all dying off except for Australia where most reside today.

When was the Pleistocene?

2.6 mil - 12,000 years ago

When was the Holocene?

12,000 years ago - present

Why is the Pleistocene so important for understanding the distributions of organisms?

The Pleistocene was a series of ice ages that allowed megafauna to flourish all over the world but kept humans restricted to Africa until its end

What is a Milankovitch cycle and why does it matter for Pleistocene glaciers?

The Milankovitch cycles are the collective effects of changes in the Earth's movements on its climate over thousands of years. Caused climate change, glacial and interglacial periods, and changes in species distribution

Eccentricity

The shape of Earth's elliptical orbit around the sun

Obliquity

Earth's tilt

Precession

Change in orientation of Earth's rotational axis

How do species respond to a changing climate? (3 responses were discussed)

1. Move
2. Adapt
3. Go extinct

Today, collared lemmings are found in arctic tundra, but we know they were once found as far south as West Virginia (and probably Ohio). How do we know that?

West Virginia was where the glaciers stopped so it would've been on the edge of their habitat.

On what continent were humans during most of the Pleistocene?

Africa

What were the Pleistocene megafauna?

Giant beaver, ground sloth, and American lion that roamed the earth during the ice ages