topic 1

Question 1

define ecology

Answer 1

ecology is the study of interactions between organisms and their environment that determine their distribution and abundance

Question 2

ecology is inter deciplinary. describe its hierarchical organization

Answer 2

each level has its own set of properties

largest to smallest: ecosphere, biome, landscape, ecosystem, community, pop, organism etc

Question 3

define population

Answer 3

• A group of interacting individuals (possibly interbeeding) individuals of the same species that occupy a given area (at a given time)
○ HAVE TO BE INTERACTING!!

Question 4

define pop ecology

Answer 4

The study of the abundance, distribution, and other population characteristics of organisms (the things we measure and study)

Question 5

how is abundance measured

Answer 5

• Abundance ( usually N or n)
○ Population size: # of individuals
○ Population density: # of individuals per unit area (or volume)
Biomass density: biomass per unit area or volume (tonnes fish/ m^3)

Question 6

why is abundance important

Answer 6

This is really important as it determines whether a species is common or rare, safe harvest levels. It also influences how populations evolve

Question 7

what is spatial distribution? types?

Answer 7

arrangement in space
○
○ Has to do with the probability of finding an individual in any given spot
uniform, random, clumpex

Question 8

what are vital rates? what does it influence? how can it vary?

Answer 8

Vital rates: birth rate (fecundity), death rate (mortality)
influences abundance
varies with age = age structure important

Question 9

describe age structure

Answer 9

• Age structure
○ Number of individuals in different age categories
○ Often separated by sex
Shape of age structure graph can tell us a lot

Question 10

describe stage structure

Answer 10

○ Population broken down by size, developmental stage, etc.

○ Ex. Balsam fir trees based on trunk size or insect that goes through stages

Question 11

describe sex ratio

Answer 11

○ Influences growth rate of pop.

Not all populations have straightforward sex ratios (asexual hermaphroditic, etc)

Question 12

describe geographic range

Answer 12

Where a species is found, larger range than spatial

Question 13

define evolution. how does it occur? what does it require?

Answer 13

• Change in the properties of populations over the course of generation
• Occurs via natural selection (adaptive evolution), but also by other processes
• May be slight or substantial
• Individual organisms do not evolve - pop.s do
Requires variation within a population

Question 14

how can genetic variation occur?

Answer 14

• Can occur between and within populations
• Variation in genotypes (genetic makeup of organism)
Variation in phenotype (genes and environment); physical, physiological, or behavioural traits

Question 15

how is pop level variation contained

Answer 15

• Population level genetic variation contained within gene pool

Question 16

what is the gene pool? what does it measure?

Answer 16

• Sum of genetic info (alleles) across all individuals in a population (total genetic variation)
• Measures of total genetic variation: allele, phenotype, or genotype frequency
Basic level at which evolution occurs, e.g., the gene poor changing over time

Question 17

3 ways genetic variation is generated

Answer 17

• Mutation
  
  • Sexual recombination
  • Immigration / gene flow
  • Mutation

Question 18

describe + define mutation

Answer 18

• Any heritable alteration of genetic material
• Change in nucleotide sequence
○ Often random process - cell division copying errors
○ Radiation, viruses, UV rays, etc
• Often a change from one allelic form to another
• May be harmful, neutral, or beneficial
Effect depends on the environment

Question 19

describe sexual recomb

Answer 19

• 1/2 alleles from each parent
  
  • Alleles dealt at random
  • Changes from generation to generation in large populations

Question 20

describe immigration/ gene flow

Answer 20

• Movement of individuals into a population
• leads to gene flow
Only contributes to genetic variation in the population if immigrants reproduce

Question 21

describe natural selection - who came up with it

Answer 21

• Charles darwin and alfred wallace 1858 - came up with the theory, both independently proposed the theory

* Organisms well adapted to their environment transmit heritable genetic characteristics to subsequent generations 
* Favors traits (adaptations) that result in an organism leaving more descendants (higher fitness) 
* Adaptive evolution maximizes fitness of individuals overtime

Question 22

describe fitness

Answer 22

• Proportionate genetic contribution that an individual makes to future generations
• Depends on individual survival and reproduction (and that of the descendants)
• Different strategies to optimize fitness
Relative term: same species

Question 23

requirements for natural selection

Answer 23

1. Variation in reproductive success
   
   2. Variation in traits / phenotype
   3. Correlation between traits and reproductive success
   4. Heritability of those traits
      If any of these are violated no natural selection will occur on that trait
      ex. pepper moth

Question 24

3 modes of selection? know the graphs

Answer 24

stabilizing, directional, diversifying

Question 25

describe stabilizing selection

Answer 25

eliminates extreme variants from pop - trend towards reduced phenotypic variation and maintains status quo

Question 26

describe directional selection

Answer 26

shifts makeup of the pop by favoring variants of one extreme.

Question 27

diversifying selection describe

Answer 27

favors variants of opposite extremes over intermediate individuals

Question 28

what does the speed of selection depend on

Answer 28

• Signficant variation, depends on: ○ Strength of selection ○ Population size - large populations typically have higher genetic variation = more likely that natural selection will act on it

Question 29

limitations to adaptation

Answer 29

``` • Adaptations are limited by: ○ Mutations and gene flow ○ Constantly changing environments ○ Historical evolutionary constraints ○ Each trait represents a trade off with costs and benefits ```

Question 30

what is net result of selection

Answer 30

Net result of selection over time: organisms become better adapted to their environment

Question 31

adaptation trade off - describe clutch size in birds - what is favored vs reality?

Answer 31

• Varies in different birds • Optimal clutch size • Natural selection should favor birds that leave the most descendants (not necessarily those who lay the most eggs) • Many birds lay fewer th • Ovulation stops before max - trade offs - putting all their energy into making eggs - cannot feed and protect them all • No organism has unlimited energy or resources • All activities have benefits and costs an their physiological max

Question 32

what are trade offs?

Answer 32

reproduction mazimized within constraints of other energy requirements (ex. feeding young, protect from enemies, defend territory)

Question 33

what is lack's hypothesis on clutch size

Answer 33

• Clutch size in birds that feed their young in the nest) was adapted by natural selection to correspond to the greatest number of young for which the parents can provide adequate food If the number of offspring is too high, the offspring quality will decline (inadequate food) - reduces overall fitness

Question 34

look at graph for cost-benefit model. which clutch size is optimal for max profit/fitness

Answer 34

ok. clutch size w/ max. difference between benefits and cost is optimal for individual profit max

Question 35

how was lack's hypothesis tested by pettifor in 1993?

Answer 35

• Blue tit - 11 eggs in nature • Prediction: fitness maximized at 11 eggs/clutch due to reductions in offspring quality at higher clutch sizes • Pettifor artificially manipulated broods ○ Added or subtracted chicks ○ Counted number of offspring surviving Support for lack's hypothesis

Question 36

deviation from lack's hypothesis?

Answer 36

additional fitness trade offs beside offspring quality: adult survival + future reproduction many species have a normal clutch smaller than most preductive based on # of offspring surviving

Question 37

benefits and costs of increased clutch

Answer 37

Increased clutch size Benefits: more descendants (+ fitness) Costs: — Energy to make eggs (can affect future survival/reproduction) — Energy to feed additional offspring ( can affect offspring quality (Lack's hypothesis) & future survival/reproduction)

Question 38

other processes that lead to variation in gene pool?

Answer 38

* Mutation and gene flow * Genetic drift - chance variation in allele or genotype frequencies from generation to generation (pronounced in small populations)

Question 39

describe genetic differentiation. how does it occur? results in?

Answer 39

• Genetic variation among subpopulations of the same species ○ widely distributed species experience a range of environmental conditions leading to genetic differentiation ○ Greater distance = greater differentiation Results in variation in particular characteristics that represent different adaptations

Question 40

what can genetic differentiation occur as?

Answer 40

* Geographic variation and resulting genetic differentiation within a subpopulations of a species can occur as: * Clines * Ecotypes * Geographic isolates

Question 41

describe clines

Answer 41

• Gradual change over a geographic region • Continuous variation in a trait or genotypic frequency • Associated with particular environmental gradients - temp, precip • Usually gene flow between populations along the gradient • ex. different in height of yarrow pops - common garden • Common garden environment used to test if its genetics or environment - is the trait retained in a common environment Often due to both factors

Question 42

look into cline more

Answer 42

ok

Question 43

describe ecotypes

Answer 43

• Marked discontinuity in traits • Reflect abrupt changes in environment ex. morphs of snail shells - H morph in crevices on cliff face = smaller, thin shell M morph on boulders on shore = larger, thick shell

Question 44

describe geographic isolation

Answer 44

• Populations isolated due to geographical features • Low gene flow between populations (little immigration and emigration) • Degree of isolate depends on geography - rarely complete May lead to specialization ex. 2 spotted owl sub species showing genetic and morphological differences - living in diff locations