ecology module 3

test 1

What is an adaptation?

An adaptation is a trait or characteristic that helps an organism survive and reproduce in its environment.

What are environmental constraints? How do organisms respond to environmental constraints?

• factors in the environment that limit an organism’s ability to survive, grow, or reproduce.

• energy acquisition

• Constraint: lack of water

• Plant response: waxy coating, deep roots, closing stomata, storing water

• Result: less water loss → better survival

What are examples of a variety of adaptations discussed in lecture.

different adapations of beetles dependent on nutrition

• dung beetles

• jumping to get food

• 
  

What is evolution by natural selection? What conditions must be met for evolution to occur?

• variation in a characteristic that is inheritable

• variation leads to differences of survival and reproduction of individuals in the population through environmental interactions

• leads to shift of alleles (diff traits diff fitness)

Know the key terms outlined in the adaptation lecture (fitness, evolution, adaptation, genotype, genome, allele gene expression, etc.)

fitness: proportionate contribution made by an individual to future generations relative to other individuals in same population (if passing on gene with diff success, allele frequency shifts towards particular individuals with higher fitness)

evolution: changes in populations of organisms over time

adaptation: any heritable behavior morphological or physiological trait evolved through process of natural selection.

genotype: homozygous or heterozygous copies of allele. alleles present at each gene within an organisms genome

phenotype: physical manifestation of those genes

genome: all of the dna in a cell

allele: alternate forms of the same gene

gene expression: diff types of cells where diff genes expressed

What is the difference between qualitative and quantitative traits?

qualitative: shows small number of discrete phenotypic categories, encoded by single protein coding gene

quantitative: continuous distribution of phenotypes, often encoded by 2 or more gene

Genetic variation occurs at the level of the population. What is genetic differentiation?

two or more populations of the same species become genetically different from each other

Genetic variation = differences within a population
Genetic differentiation = differences between populations

How do allele frequency and genotype frequency differ?

• Allele frequency = how common a specific allele is

• Genotype frequency = how common a specific combination of alleles is

What is the phenotype? How is it related to genotype? How is it affected by natural selection?

changes in temp, precip, sunlight, predation level, can all change this

favored traits /natural selection lead to growth of certain traits

Be familiar with the examples I gave in class. Be comfortable enough with the material to apply it to a novel example.

things like malnutrition changing growth height later in life

cooler climate darker bug warmer lighter

acclimation seasonal changes in temp tolerence in fish

What is the target of selection? What is the selective agent? How are they related?

target of selection is the trait or characteristic that affects an organism’s survival or reproduction.

selective agent is the environmental factor that causes some traits to be more successful than others.

Selective agent → acts on a trait → affects survival/reproduction

What are the different ways natural selection can affect the distribution of the population’s phenotype?

Directional = ONE extreme
Stabilizing = MIDDLE
Disruptive = BOTH extremes

Be able to describe/distinguish directional, stabilizing, and disruptive selection. Be able to show how traits would respond on a graph of trait distribution vs. # of individuals.

1. Directional selection → favors one extreme

   • Population shifts toward one end.

   • Example: larger beaks become more common because they are better at cracking available food.

   • Graph: peak moves left or right.

2. Stabilizing selection → favors the average/intermediate

   • Both extremes are selected against.

   • Example: very small and very large babies have lower survival than average-sized babies.

   • Graph: peak gets taller and narrower around the middle.

3. Disruptive selection → favors both extremes

   • The intermediate phenotype is selected against.

   • Example: birds with either very small or very large beaks do better, while medium beaks do poorly.

   • Graph: develops two peaks.

Many factors other than natural selection can affect genetic variation in a population? What are they? What effects can they have (as we covered in lectures)? Why do they have the effect that they do?

mutations: heritable change in chromosome

genetic drift: change in allele frequency as a result of random chance (smaller population = more affected)

migration - gene flow:movement of individuals among local populations

assortative nonrandom mating: changes in allele frequency, chose mates based on their phenotype, certain traits more favored by mateu

What is the Hardy-Weinberg principle? What does it allow us to do?

under conditions of random mating, no mutations, no genetic drift, no gene flow, the allele frequency of a population remains constant through time

no evolutionary change occurs through process of sexualreproduction itself

What are the criteria for maintaining gene/allele frequency in a population? How do we quantify this?

• No mutation → no new alleles are created

• No gene flow → no alleles enter or leave the population

• Very large population → minimizes genetic drift

• Random mating → individuals mate randomly

• No natural selection → all individuals have equal reproductive success

Allele frequencies:

p+q=1p + q = 1

• p = frequency of one allele

• q = frequency of the other allele

Genotype frequencies:

p² + 2pq + q² = 1

• p² = homozygous dominant

• 2pq = heterozygous

• q² = homozygous recessive

What is a cline?

gradual change in a trait or allele frequency across a geographic area.

What is an ecotype?Be able to recognize, give and make up examples of clines and ecotypes.

• population within a species that has become genetically adapted to a particular local environment.

• gradient of gene flow

• (differences in deer in canada vs panama) (fence lizard cline in body size, larger at higher latitudes) (number of seeds or leaves at different altitudes)

How would you test if character variation is due to ecotypes vs. phenotypic plasticity?

Take individuals from different environments/populations and raise them in the same environment.

If their trait differences remain, this suggests genetic differences and ecotypes. If the differences disappear, this suggests phenotypic plasticity.

What are geographic isolates? Subspecies?

• Geographic isolates are populations of the same species that are physically separated from each other, so they have little or no gene flow between them.

• a distinct population within a species that has developed noticeable differences, usually because it has been geographically isolated, but it can still potentially reproduce with other subspecies of the same species.

What are some of the caveats related to the adaptation of organisms that results from natural selection?

Adaptations produced by natural selection are not perfect because they involve trade-offs, evolution can only work with available heritable variation, environments change, and not all traits are necessarily adaptations. Natural selection produces traits that improve reproductive success, not perfectly designed organisms

What is adaptive radiation? What could lead to natural selection occurring over short time periods (in a relative sense).

one ancestral species rapidly evolves into many different species, with each becoming adapted to a different environment or way of life.

Example: Darwin's finches. A common ancestor colonized the Galápagos, and different populations adapted to different food sources, eventually producing multiple species with different beak shapes.

Strong environmental change + heritable variation + differences in survival/reproduction = rapid natural selection

How can climate change affect species (and their adaptations?)?

Climate changes → environment changes → selection pressures change → some traits become more/less beneficial → populations may adapt, move, or decline

What is phenotypic plasticity? Developmental plasticity vs. acclimation? How do these relate to adaptation?

• Phenotypic plasticity = an organism can change its traits in response to its environment without changing its DNA.(Example: A plant grows larger leaves in a shady environment but smaller leaves in bright sunlight.

• Developmental plasticity = the environment affects a trait while the organism is developing. A tadpole detects lots of predators → develops a deeper tail that helps it escape.

• Acclimation = an organism adjusts an existing trait after experiencing a change in its environment, usually within its lifetime. You move from Georgia to a high-altitude location.Over time, your body produces more red blood cells to help deal with lower oxygen.

How do we test to determine which causes a certain set of traits?

Same environment + traits still different = GENETICS 🧬
Different environment + traits change = PLASTICITY 🌱

Developmental plasticity vs. acclimation: You can also manipulate the environment during development to test developmental plasticity, or change the environment after development to test acclimation.

What is genetic engineering? How does it relate to natural selection?

humans directly change an organism's DNA to give it a desired trait.

differs from natural selection because humans directly create or introduce genetic changes, whereas natural selection changes the frequency of heritable traits because they affect survival and reproduction. Natural selection can still act on genetically engineered traits after they are introduced

What is artificial selection? 

How are genetically modified (transgenic) organisms "created" - at the level covered in lecture.

artificial = humans choose which organisms reproduce based on a desired trait.

A transgenic organism is an organism that has had a gene from another species inserted into its DNA.

What types of GMOs are there? What are their uses? What are the benefits discussed in lecture?Current or potential drawbacks/cons?

• research

• pharmaceutical production (how we treat diabetes, creating insulin with bacteria that produces human insuline )

• agriculture (development of insect resistant cross strings)

• issues: ecological concerns in crop species that are related to wild species. include evolution of resistance, gene flow, effects on non-target organisms,

What are some concerns about use of GMOs in agriculture?

evolution of resistant pests and weeds, movement of engineered genes into other populations, effects on non-target organisms, reduced genetic diversity, potential ecosystem effects, and economic concerns related to patented seeds

What is Bt corn? 

Bt corn is genetically modified corn that contains a gene from the bacterium Bacillus thuringiensis (Bt

Bt bacterium 🦠 → gene transferred to corn 🌽 → corn produces Bt protein → certain insects eat it → insects die

It helps reduce insect damage and may reduce insecticide use, but repeated exposure can select for Bt-resistant insects.