Ecology: Behavioural Ecology, Mating Systems, Life Histories, and Population Dynamics

Vocabulary practice flashcards covering behavioural ecology, social systems, sexual selection, life history strategies, population distribution, and demography.

Behavioural Ecology

The study of interactions between organisms and their environment that are mediated by behaviour.

Adaptive Behaviour

A behaviour that increases the survival and/or reproductive success (fitness) of an organism. It must have a genetic basis (at least in part) so it can be selected over generations, with its expression depending on both genes and the environment.

Protein Kinase G (PKG)

An enzyme coded by a single gene in honeybees that controls foraging behaviour: higher PKG expression causes bees to forage outside the hive, while lower PKG expression causes bees to perform brood care inside the hive.

Hamilton's Four Classes of Social Interaction

A classification of social interactions based on fitness consequences to the donor and recipient: Cooperation (+/+), Selfishness (+/-), Altruism (-/+), and Spite (-/-).

Inclusive Fitness

An individual's overall fitness determined by its own direct survival and reproduction plus the indirect survival and reproduction of its genetic relatives (kin).

Kin Selection

An evolutionary mechanism where individuals increase their inclusive fitness by helping increase the survival and reproduction of genetic relatives.

Hamilton's Rule

The mathematical condition under which an altruistic trait is favoured by natural selection: $R_g \times B > C$, where $R_g$ is the genetic relatedness between donor and recipient, $B$ is the reproductive benefit to the recipient, and $C$ is the reproductive cost to the donor.

Coefficient of Relationship ($R_g$)

The probability that alleles at a given locus are identical by descent between two individuals in a population (e.g., $0.5$ between parent and offspring; $0.25$ between grandparent and grandchild).

Cooperative Breeders

Species in which individuals live in groups and several adults assist with defending territory, maintaining living spaces, and feeding young that are not exclusively their own.

Eusociality

A highly complex form of sociality defined by three characteristics: individuals of multiple generations living together, cooperative care of young, and division of labour into sterile/non-reproductive and reproductive castes.

Haplodiploidy

A sex-determination system in Hymenoptera where males develop from unfertilized haploid eggs and females develop from fertilized diploid eggs, resulting in sisters sharing $75\%$ of their genes by descent and only $50\%$ with brothers.

Altruism by Manipulation

A situation where a host displays seemingly altruistic behaviour (such as raising the offspring of an obligate brood parasite like a cowbird) because the host lacks the ability to recognize or prevent the parasitic interaction.

Spite

A rare social interaction that results in fitness disadvantages for both the donor and the recipient (e.g., chronically infected European badgers leaving kin and spreading bovine tuberculosis to non-kin).

Anisogamy

A form of sexual reproduction involving the fusion of two gametes that differ distinctly in size and energetic cost (large, nutrient-rich eggs versus small, motile sperm).

Instantaneous Hermaphrodite

An organism capable of performing both male and female reproductive functions simultaneously (e.g., earthworms and slugs).

Sequential Hermaphrodite

An organism that changes its sex over the course of its life; can be protandrous (male first, changing to female) or protogynous (female first, changing to male).

Social Monogamy

A mating system where a male and female form a pair bond and cooperate to raise offspring, though fidelity may be incomplete due to extra-pair copulations.

Polygyny

A mating system in which one male mates with multiple females during a reproductive period.

Polyandry

A mating system in which one female mates with multiple males; frequently associated with sex-role reversal and male parental care (e.g., jacanas).

Polygynandry

A promiscuous mating system in which multiple males mate with multiple females within a social group (e.g., bonobo chimpanzees).

Intersexual Selection

Sexual selection driven by mate choice, where individuals of one sex (typically females) select mates based on specific phenotypic traits, courtship dances, songs, or ornamentation.

Intrasexual Selection

Sexual selection driven by competition among individuals of the same sex for access to mates, favouring traits such as weapons, large body size, and aggressive behaviours.

Sexual Conflict

An evolutionary conflict arising from asymmetric mating costs and benefits between sexes, leading to an antagonistic co-evolutionary arms race between male persistence and female resistance.

Life History

The schedule of an organism's life regarding how it allocates energy and resources to grow, reproduce, and survive over its lifetime.

Principle of Allocation

The evolutionary principle that the total energy pool available to an organism is limited; energy allocated to one function (growth, maintenance, activity, or reproduction) inevitably reduces the energy available for others.

Fecundity

The number of offspring produced by an organism per reproductive episode.

Semelparity

A reproductive strategy in animals characterized by a single reproductive event in a lifetime followed by death (e.g., sockeye salmon, mayflies).

Iteroparity

A reproductive strategy in animals characterized by multiple reproductive events over the course of a lifetime (e.g., house mice, coyotes, humans).

Monocarpic Plant

A plant that flowers and sets seed only once in its life and then dies (e.g., canola, agave).

Polycarpic Plant

A plant that flowers and produces seeds multiple times throughout its lifespan (e.g., apple trees).

Ruderals

In Grime's CSR framework, fast-growing, short-lived plants that dominate environments characterized by high disturbance and low stress, allocating energy into large numbers of small seeds.

Stress-Tolerant Plants

In Grime's CSR framework, slow-growing plants adapted to environments with high physiological stress and low disturbance, prioritizing maintenance and stress tolerance over reproduction.

Competitive Plants

In Grime's CSR framework, plants adapted to environments of low stress and low disturbance with high resource availability, allocating heavy investment into vegetative growth (canopy and height).

Opportunistic Life History

In Winemiller and Rose's classification, a strategy combining low juvenile survivorship ($l_x$), low fecundity ($m_x$), and early age at maturity ($\alpha$), adapted to environments variable in space and time.

Periodic Life History

In Winemiller and Rose's classification, a strategy combining low juvenile survivorship ($l_x$), high fecundity ($m_x$), and late age at maturity ($\alpha$), adapted to predictable seasonal environments.

Equilibrium Life History

In Winemiller and Rose's classification, a strategy combining high juvenile survivorship ($l_x$), low fecundity ($m_x$), and late age at maturity ($\alpha$), adapted to stable environments with high competition.

Population

A group of individuals of a single species inhabiting a specific geographic area at the same time.

Ecological Density

The number of individuals of a population per unit area of suitable, habitable living space.

Numerical Response

A change in predator population density in response to changes in prey density, driven either by reproduction (with a time lag) or by aggregative dispersal (synchronized, without a time lag).

Random Distribution

A small-scale spatial pattern where an individual has an equal probability of occurring anywhere in an area, driven by neutral interactions and uniform resource availability.

Regular Distribution

A small-scale spatial pattern where individuals are uniformly spaced through the environment, driven by antagonistic interactions (e.g., territoriality) or uniform resource depletion.

Clumped Distribution

A spatial pattern where individuals live in patches of high local abundance separated by areas of low abundance, caused by mutual attraction, patchy resources, or dispersal limitation.

Metapopulation

A group of spatially separated subpopulations occupying distinct habitat patches that are connected by the movement and exchange of dispersing individuals.

Rabinowitz's Rarity Model

A framework classifying species commonness and rarity based on eight combinations of three factors: geographic range (extensive vs. restricted), habitat tolerance (broad vs. narrow), and local population size (large vs. small).

Cohort Life Table

A demographic tool that tracks the survival and reproductive rates of a specific group of individuals born at the same time (a cohort) from birth to the death of the last individual.

Static Life Table

A demographic snapshot recording the age at death of a large sample of individuals over a narrow time window, using anatomical structures like horn rings, growth rings, or otoliths.

Type I Survivorship Curve

A pattern where juvenile survival is high and the vast majority of mortality occurs among older individuals (e.g., Dall sheep, humans).

Type II Survivorship Curve

A pattern where individuals experience a constant, age-independent mortality rate throughout their lifespan (e.g., American robins, white-crowned sparrows).

Type III Survivorship Curve

A pattern characterized by extremely high mortality rates among juveniles, followed by high and relatively constant survival for the few individuals reaching maturity (e.g., fish, many trees).

Frequency-Dependent Selection (Sex Ratio)

An evolutionary process where the fitness of a genotype depends on its frequency in the population, maintaining an equal $1:1$ sex ratio because parents producing the rarer sex leave more grandchildren.

BIDE Model

The fundamental population growth accounting model: $N_{t+1} = N_t + B + I - D - E$, where $N_t$ is current population size, $B$ is births, $I$ is immigration, $D$ is deaths, and $E$ is emigration.

Density-Independent Factor

An ecological factor whose effect on per capita birth, death, or dispersal rates does not vary with population density (typically abiotic events like floods or temperature extremes).

Density-Dependent Factor

An ecological factor whose per capita effect changes as population density changes (typically biotic forces such as food depletion, competition, disease, or predation).

Net Reproductive Rate ($R_0$)

The average number of female offspring produced by an individual female over her lifetime, calculated as $R_0 = \sum l_x m_x$, where $R_0 = 1$ indicates population stability, $R_0 > 1$ indicates growth, and $R_0 < 1$ indicates decline.

Fecundity Schedule ($m_x$)

A tabulation of age-specific birth rates reflecting the average number of female offspring produced per female within each age class $x$.

Generation Time ($T$)

The average time elapsed between the birth of parents and the birth of their offspring, calculated as $T = \frac{\sum x l_x m_x}{R_0}$.