Biology Midterm- Monday, September 30 2013 th
Organismal Ecology: the study of how an individual interacts with its environment. The focus is on
individuals, their environment, and their evolved strategies for coping.
Population Ecology: the study of a group of individuals of a single species living in the same general area.
The geographic boundaries of a population or the point in space that separates distinct populations can
sometimes be difficult to define.
Community Ecology: Assemblages of populations of various species living close enough to potentially
Ecosystem Ecology: the study of how communities interact with their physical environment.
Landscape Ecology: the study of how components of different ecosystems interact.
Global Ecology/Biomes: the study of distinct areas of the earth characterized by the vegetation type,
climate, soil, etc. Example: the Boreal Forest extends all around the northern hemisphere.
Morphology: when an individual changes due to something in its environment.
Ontogenetic Reaction: when a single individual reacts to a change it its environment.
Evolutionary Reaction: when a population changes because different kinds of individuals predominate.
Strategy: the full set of behaviors, structures, physiological processes, etc… that an organism displays
under a particular set of environmental conditions.
The ‘Role Niche’: a species’ role, place, or nook in a community. Species apparently occupying the same
foods, behaviors, and morphologies have the same ‘role niche.’ Sometimes termed Ecological
Population-Persistence Niche: the set of conditions that sustains a population of individuals. This concept
has a precise, quantitative focus on what individuals need to survive and thrive reproductively. The realm
containing these conditions is called the fundamental niche.
Realized Niche: Competition will usually shrink the fundamental niche into a realized niche.
Resource-Utilization Niche: the set of conditions utilized by individuals in a population.
Behavior: Individuals use behavior to interact with their environment. Any individual’s behavior has many
contexts are behavioral elements: parental care, communication, territoriality, foraging, reproductive
behavior, migration, etc.
Female Reproductive Behavior: manufacture eggs, incubate eggs or fetus, post partum care, loss of
mating opportunity when pregnant: Expensive.
Male Reproductive Behavior: manufacture sperm: Cheap.
Numerical Sex Ratio: the ratio of the number of males to the number of females in the population.
Operational Sex Ratio: the ratio of the number of males to the number of females that are available to
Sessile Organisms: define sampling area and count fully or sample a limited area, and extrapolate.
Mobile Individuals: instantaneous counts or sample limited area and extrapolate.
Dispersion: a quantitative measure of how many organisms are distributed in space. Dispersion can be
clumped, uniform, or random.
Exponential Population Growth: results when populations grow continually at their maximum per capita
rate- such that the growth rate of the population is proportional to population size. This means that given
a period of time, a population will add a number of individuals equal to its growth rate times the number
of organisms in the population. Demography: the vital statistics- specific birth and death rates for organisms at particular ages. Type one:
death rate higher in older individuals. Type two: death rate constant. Type three: death rate is higher in
Life Tables: age specific summaries of the survival pattern of a population.
Cohort: group of individuals of the same age.
Controls on Population Growth; Density Independent: affect a population irrespective of the density of
the population. Examples: drought, natural disasters, food/O 2upply, etc.
Controls on Population Growth; Density Dependent: effects on a population are directly proportional to
the density of the population. Examples: competition, territoriality, predation, disease, parasites, etc.
R Selected Populations: rapid population growth; early maturity; large numbers of offspring; poor
competitors. Examples: fireweed, mosquitoes, ragweed.
K Selected Populations: slow population growth; late maturity; lower numbers of offspring; good
competitors. Examples: Humans, Oak trees, tortoises.
Diversity: measures of diversity may evaluate the number of species, as well as the number of organisms
in each species in an area. Two independent components of diversity: the number of distinct species, the
relative number of individuals of each species.
Keystone Species: a species that strongly influences the structure of a community.
Disturbance: Any event that changes a community, removes (or adds) species, or alters resource
availability. Examples: floods, glaciers, fire, hurricanes, invasive species, etc. Regular events- so
communities are regularly changing or adjusting to altered conditions.
Succession: Replacement of species in a habitat through a regular progression. Occurs usually after some
Secondary Succession: Some soil or organic base left in a community, giving a biotic ‘head start.’
Primary Succession: Community is wiped out to abiotic state, ‘blank slate.’
Competition Exclusive Principle: When two species compete for the same limited resource, one species
will eventually eliminate the other. (Must be competing for the same resource)
Ecological Niche: the total of the species’ use of biotic and abiotic resources in its environment.
Resource Partitioning: differention of ecological niches to a degree that allows two ecologically similar
species to co-exist. Example: the Bay-Breasted Warbler, Cape May Warbler, and Myrtle Warbler all eat
roughly the same food and live in the same trees.
Mutualism: any interaction that is (+,+) between members of two species that is beneficial to both.
Benefits must be scientifically tested and not simply assumed.
Predation: A (+,-) interaction between members of two species in which one species kills and eats
members of the other.
Trophic Structure: feeding relationships between populations. Largely determines community structure
and dynamics. Examples: food chains, food webs.
Top Down Mechanism: a unidirectional influence from higher to lower trophic levels.
Bottom up Mechanism: a unidirectional influence from lower to higher trophic levels.
Ecosystem: All the organisms in a given area as well as the abiotic (physical) factors in which they interact.
A system that transforms energy, processes organic matter, and passes chemicals.
Primary Producers: all photosynthetic organisms. These are photautotrophs that fix carbon and allow it to
be used at other levels. Examples: plants, algae, phytoplankton.
Primary Consumers: All plant eating organisms. Herbivores, Heterotrophs.
Secondary Consumers: predators, all are heterotrophic organisms.
Detrius: dead organic matter. Detrivores/Decomposers: organisms that eat dead organic material.
Gross Primary Production: GPP is the sum total of all carbon fixed by plants in any ecosystem. Plants must
use some of this fixed energy for their own cellular metabolism/respiration.
Net Primary Production: NPP is what is available to the next trophic level. Food chains trace the fate of
NPP through each of the levels.
Standing Crop: total dry weight of all organisms at a trophic level in any ecosystem at a point in time. Key Ideas
The best choice for an organism may change with a change in environment. The best choice maximizes
the difference between benefits and costs. For example, the choice of strategy for a male guppy: Be dull
coloured and avoid predators, yet attract no females. OR, be brightly coloured, be conspicuous to
predators, and attract many females. The key elements of the environment and strategy are particular
to each species.
An organism can react to its environment in many ways- by behavior, physiology, and morphology.
Generally, males invest less in any one offspring. Females expend lots of time and metabolic energy in
reproduction, resulting in a greatly decreased number of females available for mating. Males expend little
time and metabolic energy in reproduction, resulting in a lesser decrease in the number of males available
for mating. Therefore, females make a large investment in each mating while males make a small
Females may maximize reproduction by choosing particular mates. Males may maximize reproduction by
mating with more partners. These are conflicting strategies. As a consequence, females become limiting
to male reproduction and access to female mates becomes a major determinant of male behavioral
If a male does something extra to enhance the survival of the eggs he has fertilized, the something extra
reduces the investment by the female, and more offspring should be able to be produced. More offspring
are then produced that carry the trait for providing something extra, and the same trait increases in
frequency in the population.
The something extra could be a resource that directly benefits the female’s capacity to reproduce, or it
could be the offering of a signal of genetic quality that was indirectly benefit the female’s reproductive
capacity through positive effects in the offspring.
Females may respond to structures used in courtship- such as territoriality- when males establish and
defend territories that have resources females need. Or, the males may offer food, or other nutrients
such as a spermatophore- sperm that contains nutrients for the female. Lastly, the male may offer care
of the offspring.
In summary: males invest less time or energy than females in reproduction. Males as a result are selected
to be more promiscuous. Males respond with courtship, resource pr