Ecology - Test Two

An explanation of the natural world or the world around you that can be proven by the scientific process.

What is a scientific theory?

Why do you think evolution via natural selection is ranked among the top ten scientific theories of science? 

because it explains so much about the world around us and better understand why the world around us is the way it is.

What are the 6 facts of the theory of evolution?

1. Populations have the potential for exponential growth (Malthus)

2. Population size does not change dramatically over time

3. Resources needed for survival are limited

4. Variations exist among individuals in a species

5. The Earth is frickin old (Lyell)

6. Offspring resemble their parents

What are the 3 inferences for the theory of evolution?

1. Individuals struggle to survive (Malthus)

2. Natural Selection - individuals with more favorable variations will produce more offspring (Darwin & Wallace)

3. Evolution - individuals with more favorable variations will become more common in a population (Darwin & Wallace)

_______ is the genetic change in a population over time.

evolution

______ ______ is when organisms with favorable genetic traits produce more offspring adding more genes to the future population than non-favorable genetic traits.

natural selection

__________ occurs when two new populations are formed from one original population that has evolved in such a way that the two new populations can no longer interbreed (can be either allopatric or sympatric).

speciation

_______ ________  is when similar phenotypes evolve independently in species without a shared common ancestor.

Convergent evolution

_______ _______ is when two species evolve in diverse directions from a common point.

Divergent evolution

An __________ is a trait that increases an organism’s ability to survive and reproduce in its environment.

Adaptation

·       What are some examples of evidence for evolution? Give at least 3 examples, here.

1.    Wild mustard is an example of variation within a species because it is responsible for, just to name a few, kale, cabbage, and broccoli.

2.    A fossil found shows the transition from a land organism to a flying organism which is an example of an extinct species resembling a living species in a similar area.

3.    The bone structure in the forelimbs of humans, cats, whales, and bats have similar structures even if they are all for dissimilar purposes.

The 4 common misperceptions of evolution

1. Evolution is just a theory

2. Individuals evolve

3. Evolution explains the origin of life

4. Organisms evolve on purpose

In science, a theory is a body of thoroughly tested and verified explanations/observations of the natural world, commonly people use the word “theory” to mean a guess. This implies there is little evidence for evolution, which is incorrect.

Evolution is just a theory (why is this wrong)

1.    Evolution is a genetic change over a long amount of time. Individuals don’t change over their lifetime, but they instead have development that involves programmed characteristics from birth.

why is saying individuals evolve wrong

 Evolution does not try to explain the origin of life. Evolution explains how populations change over time and how life diversifies the origin of species. Not how life began. Although it may show how pre-living entities acquired certain properties.

Why does evolution not explain the origin of life

Evolution is not intentional so saying organisms evolve in response to an environmental change is incorrect. The variations that natural selection works on already exist in a population and do not arise in response to an environmental change. (evolution is not goal directed)

Why is it wrong to say organisms evolve on purpose

Define a species

• A species is a group of individual organisms that can interbreed and produce fertile, viable offspring.

define a population

• A population is a species that shares a gene pool. Or in other words a collection of all the variations of genes in a species.

Why is variation in a species important

• In order for natural selection or evolution to happen there must be variation present in a species’ genotype. Without variation in a species natural selection and evolution won’t happen because there is nothing to change to if everything stays the same.

What is the original source of genetic variation

mutations

How is genetic drift different from natural selection

• Genetic drift is a random event that changes the frequency of an allele in a population while natural selection happens when an organism with a favorable genetic trait is able to reproduce than a organism with a less favorable genetic trait and not because of chance like genetic drift is.

allopatric speciation

• Allopatric speciation is when a population is geographically (such as when a new valley is formed or a new branch of a river is formed) separated from the original population. The separated population can no longer return to the original population and then evolves.

sympatric speciation

happens within the original population and is when gametes have too many or too few chromosomes due to nondisjunction during meiosis.

What role does sexual reproduction play in generating variation in a population

Two sets of genes are coming together to create the offspring

adaptive radiation

speciation following expansion of one or a few into new geographic areas (happens rapidly)

Example of adaptive radiation

The many marsupials in Australia and Darwin’s finches

stabilizing selection

A selective force/forces that push the pop. towards the average/median trait.

Directional selection

The pop. evolves towards one extreme or another on the trait spectrum

disruptive selection

traits go against the average invid. in the pop.

How is genetic drift related to inbreeding

Genetic drift can cause only a small portion of a population being left that are able to breed with can cause inbreeding with the low number of individuals

inbreeding depression

the reduced biological fitness which has the potential to result from inbreeding

bottleneck effect

Only a few individuals from a population survive to have offspring after an event

Example of a bottleneck effect

an oil spill kills off a majority of a fish population.

• What is likely to happen to populations that have gone through bottleneck?

decreased fitness/success in offspring and a higher likelihood of negative recessive traits being expressed. As well as inbreeding and an inbreeding depression

founder’s effect

• When a small group of individuals breaks off from a larger population to establish a new colony

examples of the founder’s effect

Amish people are more likely have extra fingers and toes

impacts of the founder’s effect

1. genetic structure changes to match that of the new pop.’s founding mother and father.

2. Genetic diseases become more concentrated

   1. increased likelihood that recessive alleles carrying mutations on the 4th chromosome are passed on

Why is it easier for species to emerge through allopatric speciation rather than in sympatric speciation?

in allopatric speciation a pop. only has to be separated from the og pop. and continue to survive in sympatric a change has to occur in the og pop. and survive long enough to continue that change

• How can polyploidy result in sympatric speciation?

Polyploidy is when an organism has an extra set(s) of chromosomes which causes speciation within the origina pop.

example of rapid microevolution

Galapagos finches, antibiotic resistance

transitional fossils

A fossil that shows an intermediate state between an ancestral trait and that of its later descendants

How do transition fossils relate to our understanding of macroevolution

Transition fossils show us how an organism changed over time (the developmental stages) such as the development of forearms from fins.

what did we learn from Archaeopteryx

that birds had feathers before flight (tail and wing feathers), still had teeth, long boney tails still, there is a close link between birds and reptiles.

What did we learn from Tiktaalik?

that forelimbs are modified fins, evolutionary transition between swimming fish and their descendants, the four-legged vertebrates.

what was the original function of feathers and what organisms had them?

feathers were used for insulation, courtship, and territorial displays. Reptiles had feathers first.

ploidy

the number of full sets of chromosomes a cell has

What are diploid cells

two complete sets of chromosomes where each parent contributes one pair

haploid cells

cells have a single copy of each chromosome

what process forms haploid cells

what process forms through meiosis (prophase I, metaphase I, anaphase I, telophase I)

costs of asexual repro.

1. Accumulation of mutations

2. Limited genetic variation – what if environment changes?

benefits of asexual repro.

• Maximize your own genes in offspring

• No need for mate (less risk and energy)

costs of sexual repro

• Cost of search for a mate

• Risky (disease, violence, no mates, etc.)

• COST OF MEIOSIS (parent only passes on 50% of genes)

benefits of sexual repro.

• Offspring are variable

• Purge mutations

What is the cost of meiosis

(a) the female that uses asexual reproduction contributes eight copies of her genes

(b) In contrast, the female that uses sexual reproduction only contributes four copies of her genes

chromosomal sex determinism

when the gender of an organism is determined by their sex chromosomes (ex: XY, YY, ZW, ZZ)

environmental sex determinism

Environmental sex determinism is when sex is determined by aspects of the environment not by genetics. (ex: temperature-dependent sex)

haplodiploidy

Haplodiploidy is mostly seen in social insects and is when the females are diploid and the males are haploids.

what does it mean if an individual organism is hermaphroditic

If an individual organism is a hermaphroditic it means they can produce both eggs and sperm.

How could the fact that parasites (bacteria and viruses in particular) evolve very rapidly act as a very strong selective force for sexual reproduction?

Organisms need to change and combat the parasite rates and the fastest way to create change is through sexual repro. compared to cloning

Red Queen Hypothesis

Sexual reproduction results in variable offspring which allows some offspring to survive in world of rapidly evolving pathogens (viruses, bacteria, fungi, parasites)

Why do we see higher rates of sexual reproduction in populations that are experiencing high rates of parasitism and/or pathogens?

Because of sexual repro. can cause variation very quickly (within one gen) to help combat rates

What is anisogamy?

differences in gamete size lead to differences in number of offspring that can be produced

how does anisogamy relate to the fact that males are often showier, larger, and non-selective in mate choice.

males want to be able to attract as many mates as possible and then be able to father as many offspring as possible

sexual selection

how an organism picks a mate. Can be intersexual selection (members of the same sex compete in direct encounters) or intrasexual selection (interactions between genders; behavioral displays & morphological traits)

intrasexual selection

interactions between sexes

what does intersexual selection result in

showy males, behavioral displays.

what is intersexual selection

members of the same sex compete with rivals in direct encounters

what does intrasexual selection result in?

antlers, large body size, choosy females.

Why would you predict that the sex with the greatest variability in reproductive success would be more likely to show sexually selected traits?

because of the variability in success the potential mate must compete more to be chosen by the female (has to stand out and look like the best option)

what does a female gain from being choosy

better genes to be passed on to her offspring for their survival, protection, food, avoid disease, child care help

mate gaurding

preventing other potential mates from getting access to a mate

sperm competition

some sperm moves faster inside the female to compete with other potential fathers

How can Handicap Principle, Sexy son hypothesis, Parasite Mediated Sexual Selection explain the evolution of bright colors and extreme traits (like super long tail in a peacock?)

females will pick males that have “good genes”/extreme traits reinforcing the passing down of these traits. The males are able to survive with this extreme traits (handicaped).

fundamental niche

range of abiotic conditions where a species can persist

realized niche

actual range of abiotic & biotic conditions where a species can exist

ecological niche

range of resources & conditions allowing the species to maintain a viable population

Ideal free distribution

mobile organisms distribute in enviro. to reflect max resource untilization

The 2 assumptions for max/recapture to work

1. likelihood of recapture is equal to first capture

   1. no individuals are emigrating/immigrating from pop. during marking and recapture

equation to estimate pop. size

N=Mn/m

N is

pop. size to be estimated

M is

number initally makred

n is

number subsequently captured

m is

number of n that are tagged

Polyandry

the mating pattern where a female mates with several males.`

Monogamy

a form of sexual bonding involving an exclusive pair bond between two individuals lasting at least for a breeding season or longer (Monogamy can be social or genetic).

Promiscuity

when there is no mating within a set social group (not exclusive and with no mating bond)

polygynandry

   when there is mating within a social group; a multi-male multi-female mating system (ex: a male/female mates with multiple females/males during a breeding season)

What is the difference between social monogamy and genetic monogamy? 

social monogamy is when mates both care for offspring care even if they have extra partners, genetic monogamy has bonding pairs.

how is gender determined in mammals

by sex chromosomes XX or XY

how is gender determined in birds

in the sex chromosomes ZZ (male) and ZW (female)

how is gender determined in reptiles?

by the temp. of the envrio. as the eggs are incubating (temperature-dependent sex determination)

How is gender determined in insects (X-O system)

females inherit a pair (XX) males only get an X

how is gender determined in haplodiploid systems

1. females are diploid; males are haploid

2. Queen is the only one who can produce gametes

   1. Can fertilize her own eggs

How is climate change affecting envrio. determined sex?

sea turtles need cooler temps. to produce male turtles but with climate change, it is getting too warm for males to hatch leading to 99% being females

·       If a female could determine the sex of her offspring could there be instances where producing one or the other sex could be advantageous? 

a female can produce only females through cloning when food is plentiful and their survival is insured (in spring and summer) and then begin producing males as food levels dwindle to insure eggs she lays will be fertilized when there is a chance for better survival.

species range

the region where a species can be found

what determines a range

environmental conditions and the presence or absence of other species.

how can global climate change impact a species range

o   As our global climate changes can cause an organism to have to head further North or to higher elevations that they are adapted to. This can also cause fruit seeds to be dispersed in a lower-elevation environment that has gotten too warm for them to be in now.

Why are introduced species from the same biome particularly problematic?

because the introduced species is equipped for the biome (can easily take over) but the species that are og from there are not prepared to fight off that new organism

·       Ash trees are dying on our campus – because of the emerald ash borer (EAB) – you should know the story. 

EAB was accidentally introduced in 2002 (first being spotted in Ontario)