Exam 2

Question 1

Define life cycle

Answer 1

The stages of an organism’s life from birth to reproduction to death. They provide the framework for growth and reproduction.

Question 2

Define life history traits

Answer 2

measurable characteristics that influence an organism’s fitness within its life cycle, such as birth, growth rate, age at maturity, reproductive investment, and lifespan. These traits vary across species and are shaped by environmental factors (ecological pressures).

Question 3

Define life history theory

Answer 3

Explains how natural selection shapes life history traits through trade-offs in resource use, optimizing survival and reproduction. (Since organisms have limited time, energy, and resources, natural selection favors strategies that optimize survival and reproduction under specific environmental conditions.)

Question 4

define r-selected species

Answer 4

prioritize rapid reproduction with many offspring, short lifespans, and minimal parental care (e.g., insects, rodents)

Question 5

Define K-selected species

Answer 5

invest heavily in fewer offspring, have longer lifespans, and provide more parental care, thriving in stable environments with resource competition (e.g., elephants, humans)

Question 6

What are the limitations of r and K selection models?

Answer 6

• Some species don’t fit into either model, like bats: despite being small (like r-selected species), some species invest a lot of care into their offspring (like K-selected species)
• Long-lived trees don’t fit well because because they produce many seeds (offspring) but invest little in individual ones

Question 7

When is semelparity favored?

Answer 7

favored when reproductive successes increases dramatically with high effort (e.g., periodical cicadas and some rainforest trees)

Question 8

When is iteroparity favored?

Answer 8

favored when reproductive successes level off after a small effort, conserving resources for future reproductive cycles

Question 9

Define predator saturation theory

Answer 9

Semelparous species produce an overwhelming number of offspring in one event to “flood” the environment, ensuring that some survive despite predation

Question 10

What are the different kinds of spatial distributions?

Answer 10

Clumped, uniform, random

Question 11

Define clumped spatial distribution

Answer 11

most species show this type of distribution. This occurs due to resource availability, social behaviors, or environmental factors (e.g., elephants, schooling fish)

Question 12

Define uniform spatial distribution

Answer 12

evenly spaced individuals. Often due to territorial behavior or competition for resources (e.g., penguins)

Question 13

Define random spatial distribution

Answer 13

no predictable pattern, usually seen when resources are abundant, and there is little interaction between individuals (e.g., spiders, dandelions, trees in tropical rainforests)

Question 14

Define dispersal

Answer 14

movement of individuals from one location to another, usually one-way. Essential for gene flow and new population establishment.

Question 15

Define migration

Answer 15

intentional, often seasonal movement (back and forth) of populations between two locations for resources like food, breeding, or optimal temperatures.

Question 16

How does insect migration differ from animal migration?

Answer 16

insect migration might not follow a strict return pattern; some insects may not survive the entire migration journey, so migration may span multiple generations

Question 17

Define community science and its importance

Answer 17

Community science engages the public in scientific data collection to help ecologists track geographic distributions, migration patterns, and environmental changes, providing large datasets that would otherwise be difficult to obtain

Question 18

Define ecological niche

Answer 18

Specific environmental conditions and behaviors that allow a species to persist and reproduce

Question 19

What is Hutchinson’s n-dimensional model?

Answer 19

Theoretical model; defines a specie’s niche as the n-dimensional space where each dimension represents a resource or environmental condition required for survival

Question 20

What is the difference between a fundamental niche and a realized niche?

Answer 20

Fundamental niche: full range of conditions a species could theoretically occupy
Realized niche: actual niche a species occupies due to factors like competition and predation

Question 21

What are natural resource utilization curves used for?

Answer 21

• Graphically represent the usage of resources within a niche
• Helps determine which parts of a fundamental niche are optimal or preferred
• Often visualized with histograms showing resource use across different environmental factors

Question 22

What features of a population make it either easy or difficult to count?

Answer 22

• Easy to count: unitary organisms (humans, elephants) where individuals are distinct and countable
• Difficult to count: clonal organisms (corals, mushrooms, many types of plants) because they spread in a way that makes it hard to distinguish individuals

Question 23

What is the difference between a genet and a ramet?

Answer 23

ramet: individual offshoot or branch of a single genetic organism (e.g., individual blades of grass in a clonal plant)

genet: single genetic individual that arises from a singular source (egg, seed, spore) that can produce multiple physically distinct but genetically identical units (ramets)

For example, in a mushroom patch, each visible mushroom (ramet) is connected underground by mycelia, forming one genet.

Question 24

What are examples of differences between a genet and a ramet?

Answer 24

Coral example: a genet is the original colony that arose from a single larva. Individual coral polyps that form on the reef are ramets, because they can sometimes break off and form new colonies elsewhere
Dandelion example: genet is the original dandelion plant that arose from a seed. Clones that emerge from plant reproduction (root fragments or offshoots) are ramets, because they are each capable of growing into a new dandelion.

Question 25

Define discrete reproduction

Answer 25

offspring are produced at specific intervals (seasonal breeders like wolves). Modeled using difference equations like the geometric growth model.

Question 26

Define continuous reproduction

Answer 26

offspring can be produced at any time (humans, bacteria). Modeled using exponential and logistic growth models.

Question 27

How is the mark-recapture method used to estimate population size?

Answer 27

- Set of individuals is captured, marked, and released (M1). - Second sample is taken later (NS2) and the number of marked individuals recaptured - (M2) is counted. - Assumes that the proportion of marked individuals in the second sample represents the proportion in the entire population *Population estimate (Nest) equation: Nest = (M1 * NS2) / M2

Question 28

What is the accumulation curve analysis and when is it used?

Answer 28

- Used when direct observation is difficult (elusive, dangerous, or endangered species). - Involves collecting genetic material (hair, feathers, feces) to identify unique individuals. - The estimated population size corresponds to the asymptote of the accumulation cure (the point where new unique individuals no longer appear in samples)

Question 29

What are the different population models?

Answer 29

Geometric growth model, exponential growth model, logistic growth model

Question 30

When is the geometric growth model used?

Answer 30

used for species with discrete reproduction (e.g., wolves, annual plants). Predicts population size at future time steps

Question 31

When is the exponential growth model used?

Answer 31

used for species with continuous reproduction under ideal conditions.

Question 32

When is the logistic growth model used?

Answer 32

used when populations approach a carrying capacity due to environmental limits.

Question 33

Why are small populations at risk of losing genetic diversity?

Answer 33

- Genetic drift: in small populations, random changes in allele frequencies have a smaller effect and lead to loss of genetic variation over generations - Inbreeding: fewer mating options so individuals are more likely to mate with relatives, increasing homozygosity - Effective population size (Ne): is smaller than actual size: not all individuals contribute equally to reproduction due to factors like age, social structure, and an uneven split of gender. Fixation of alleles: rare alleles can be lost, and harmful alleles can become fixed more easily in smaller populations.

Question 34

What causes Allee effects?

Answer 34

difficulty finding mates in sparse populations, reduced group defense against predators, decreased foraging efficiency (can’t hunt/gather food in groups), higher emigration rates (individuals may leave areas where populations are too small to sustain necessary social structures)

Question 34

What is an Allee effect?

Answer 34

Populations at low densities experienced reduced per capita growth rates (r) because there are so few potential mates so their population size decreases further, making it difficult to recover *only happens in small populations

Question 35

How do you calculate and interpret net productive rate (R0) using a population viability analysis (PVA)?

Answer 35

Equation: R0 = Sigma(Ix * bx) Ix: proportion of individuals surviving to age class x bx: mean number of female offspring produced per female per year in age class x interpretation: - R0 > 1: population is growing - R0 = 1: population is stable - R0 < 1: population is declining, indicating risk of extinction

Question 36

What are the three hypothesis that explain why invasive species are so successful?

Answer 36

Enemy release hypothesis, evolution of increased competitive ability (EICA), resource hypothesis

Question 37

Define enemy release hypothesis

Answer 37

invasive species escape their natural predators, parasites, and diseases from their native range, allowing uninhibited growth

Question 38

Define evolution of increased competitive ability (EICA) hypothesis

Answer 38

without the need to defend against their natural enemies, invasive species redirect energy toward growth, reproduction, and competitive dominance

Question 39

Define resource hypothesis

Answer 39

some invasive species find better resource availability (e.g., nutrients, climate, light) in their new habitat, allowing them to outcompete native species

Question 40

Why are deer more abundant today - especially in urban areas - than in pre-European settlement times?

Answer 40

- Loss of predators (wolves and cougars which historically controlled deer populations have been eliminated) - Improved forage from agriculture (farming provides abundance of food) - Edge habitat increase (urbanization and deforestation create favorable conditions) - Warm winters and urban heat islands (warmer temperatures in urban areas reduce winter deaths) - Hunting restrictions and decline in hunters

Question 41

Why might K become lower after deer have temporarily exceeded their carrying capacity?

Answer 41

- Habitat degradation (habitat becomes less capable of supporting large populations–overgrowth of population depletes food resources and plant communities) - Soil erosion (high deer density leads to loss of vegetation) - Increase in invasive species (native vegetation loss allows for invasive plants to spread) - Reduced habitat for other species (overgrowth of deer population reduces overall biodiversity)

Question 42

Define social carrying capacity

Answer 42

Maximum number of deer that people are willing to tolerate before taking action (e.g., culling, sterilization, hunting)

Question 43

Summarize the Suraci (Fear of Humans as Apex Predators) study

Answer 43

- Experiment and methods: conducted experiment in Santa Cruz mountains, broadcasting human voices versus control sounds (tree frogs) across 1 km squared spaces. Used cameras to observe behavior changes in mountain lions, medium sized carnivores, and small mammals - Findings: mountain lions avoided human sounds and moved more cautiously. medium-sized carnivores became more elusive and reduced foraging. small mammals increased habitat use and foraging.

Question 44

Summarize the Honisch (Geological Record of Ocean Acidification) study

Answer 44

- Experiment and Methods: This study reviewed geological records from the last 300 million years to identify past ocean acidification events. Researchers used isotopes and trace elements to reconstruct historical ocean pH and carbon saturation levels. - Findings: The study revealed that rapid increases in CO2 were connected to major extinctions of marine organisms that build shells (calcifiers). No past event exactly matches today’s rapid pollution levels caused by humans in terms of speed and intensity. Additionally, ocean acidification, alongside other environmental stressors, has historically led to major ecological changes.

Question 45

Summarize the Haddad (Habitat Framentation Effects) study

Answer 45

- Experiments and methods: synthesized results from long-term fragmentation experiments across five continents over 35 years. analyzed forest cover data and ecosystem impacts of reduced habitat size, increased isolation, and edge effects - Findings: fragmentation reduced biodiversity and biomass, altering nutrient cycles. Effects are strongest in smaller, isolated fragments and worsen over time. Urges conservation efforts to improve landscape connectivity to mitigate biodiversity loss

Question 46

Summarize the Powell (Resident Yellow Warblers vs. Wintering American Redstarts for territories) study

Answer 46

- Experiments and methods: Researchers removed Yellow Warblers from specific areas where Redstarts lived and then tracked the movements and health of Redstarts.as body condition and return rates - Findings: Yearling male Redstarts moved into the space left by Yellow Warblers, while adult males with overlapping territories had worse health and lower chances of returning the next year. This shows that competition affects Redstarts negatively.