APES Ch 7: Species Interactions, Ecological Succession and...

Mutualism (+/+)

interspecific interaction where both species benefit.

Parasitoids

parasite that lays eggs inside other organisms. When the eggs hatch, the organism consumes the host from the inside out, causing death.

Logistic Growth Model

population growth is initially exponential, but slows as it approaches the carrying capacity. • S-shaped curve- when graphed the logistic growth model produces an "S".

K-selected species

population of a species that grows slowly until it reaches carrying capacity. • low intrinsic rate of growth (r) so the abundance of the species is largely determined by carrying capacity (K). • Reproduces later in life, few offspring, invest in parental care, long life spans. • Examples: large mammals and birds of prey. (elephants, whales, and humans) Example plants isaguaro cactus, redwood, tropical rainforest trees.

Density-independent factors:

population size has no effect on the individual's probability of survival.

Population Age Structure:

pre-reproductive, reproductive and post-reproductive.

Ecological Succession:

process in which communities of species in a particular area are replaced over time by a series of different, more complex communities. 3 major types pf succession: primary, secondary, degradative

range of tolerance (influences pop size)

the limits to the abiotic conditions that a species can tolerate

Population density (influences pop size)

the number of individuals in a population found within a defined area or volume.

Symbiotic Relationship-

the relationship of two species that live in close association with each other

Competition (most common species interaction)

the struggle of individuals to obtain a limiting resource.

Population size

the total number of individuals within a defined area at a given time. (Immigration + Births) - (Emigration + Deaths)

Predation (can be true predators, or herbivores)

the use of one species as a resource by another species. (+/-)

Density-dependent factors

- the size of the population will influence an individual's probability of survival. Example: availability of food resources, parasites and disease.

No population can grow indefinitely because ...

...because of limitations on resources and because of competition among species for those resources.

Five types of species interactions affecting resource use and population sizes

1 interspecific competition, 2 predation, 3. parasitism, 4. mutualism, 5. commensalism

Variations of the Logistic Model

If food becomes scarce, the population will experience an overshoot by becoming larger than the spring carrying capacity and will result in a die-off, or population crash

exponential growth model desc. cont.

J-shaped curve - when graphed the exponential growth model looks like this. • Members of populations that exhibit this growth typically reproduce at an early age, have large numbers of offspring, and reproduce frequently (ex. Bacteria and many insects)

Predator strategies and examples

Pack hunting, Poisons, Adaptations, Speed, Sharp teeth/claws/eyesight

Resource Partitioning

two species divide resource based on differences in species' behavior or morphology;

Commensalism (+/0)

- a type of relationship in which one species benefits but the other has little if any beneficial or harmful effect on the other.

r-selected species

- species with a capacity for a high rate of population growth (r). • Organisms have short life spans, produce many, usually small offspring and they give little to no parental care.

Distribution of species around the world is determined by three factors:

1. Range of abiotic conditions that it can tolerate 2. Must be able to disperse to that area 3. Interactions with other species

Three Types of Resource Partitioning:

1. Temporal - utilize resource at different times (Ex: flowering at different times of the year) 2. Spatial - using different habitats. (Ex: birds utilizing different areas of the same tree as food sources) (EX: insect-eating warblers) 3. Morphological - reduces competition via evolution of different body sizes and/or shapes. (EX: Honeycreeper birds in Hawaii, Galapagos Finches)

Prey Defense Mechanisms

1• Behavioral ( ex. hiding clownfish ) 2• Morphological (Camouflage, spines) 3• Chemical - (toxic or distasteful to their predators) 4 • Mimicry - mimicking other prey species that do have chemical

• Limiting resource

: a resource that a population cannot live without which occurs in quantities lower than the population would require to increase in size.

Parasitism

A relationship between two organisms of different species where one benefits (parasite) and the other is harmed (Single parasites will rarely cause the death of its host. (EX: tapeworms) P_____ helps keep populations in check

Competitive Exclusion Principle

Ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time. Under a given set of environmental conditions, one species will perform better and will drive the other species to extinction.

interspecific competition

Species compete for a limiting resource. (-/-)

Reproductive Strategies

Species vary in their productive patterns. Most species fall somewhere in between the two extreme reproductive strategies. r-selected and K-selected.

Carrying Capacity (K):

The limit of how many individuals in a population the food supply can sustain. (Helps scientists predict how many individuals an environment can sustain)

survivorship curve

a graph that represents the distinct patterns of species survival as a function of age

exponential growth model

a mathematical description of idealized, unregulated population growth

Eutrophication: Aquatic Succession

gradually lakes become richer in organic material and in concentrations of inorganic nutrients such as N and P. As organic materials accumulate, the lake basin fills in, becoming a terrestrial habitat.

Population sex ratio - the ratio of males to females; usually about 50:50.

helps scientists estimate the number of offspring a population will produce in the next generation.

Secondary succession

occurs in areas that have been disturbed, or destroyed, but have not lost all their soil. Places where this occurs includes: abandoned farmland, burned or clear cut forests, flooded land, polluted streams. • Takes less time than primary succession and begins with annual weeds followed by perennial weeds and grasses.

Primary succession

occurs on surfaces that are initially devoid of soil or bottom sediment. Places where this occurs includes: bare rock exposed by a retreating glacier, newly cooled lava, abandoned parking lot, newly created shallow pond or lake. Usually takes hundreds to thousands of years.

exponential growth model desc

• Growth rate - the number of offspring an individual can produce in a given time period, minus the deaths of the individual or offspring during the same period. • Intrinsic growth rate (r) - under ideal conditions, with unlimited resources, the maximum potential for growth. • Nt= No•e^rt where Nt is future size of the population, No is current size of the population, r is intrinsic growth rate, and t is amount of time over which the population grows.

population distribution

• Random • Uniform • Clumped

Survivorship Curves (3 types)

• Type 1 (Late Loss): high survivorship throughout life cycle. At old age, die off in larger numbers. Typical of K-selected species typically. • Type II (Constant Loss): survivorship w/constant proportion of individuals dying over time. (ex. Song birds/ squirrels) • Type III (Early Loss): survivorship v. high mortality at young ages; few reach adulthood. Typical of r-selected species • Most real populations are some mix of these three For example, survivorship of juveniles for some species is Type III, but is followed by type I survivorship for the adults.