2.1 Species and Populations Flashcards
Define species
a group of organisms that share common characteristics and that interbreed to produce fertile offspring.
Define habitat
The environment in which a species normally lives
Define niche
describes the particular set of abiotic and biotic conditions and resources to which an organism or population responds.
Distinguish between biotic and abiotic (physical) components of an ecosystem
The main difference between biotic and abiotic factors is that biotic factors are comprised of living things (such as plants, animals, and fungi). In contrast, abiotic factors are comprised of non-living chemical and physical environmental conditions in an ecosystem (such as wind, water, and light).
Distinguish between fundamental and realized niche with reference to a named example
Fundamental niche: theoretical niche, which describes the full potential of where, when and how a species can exist
realised niche: where the species actually exists
List the significant abiotic (physical) factors of an ecosystem.
The chemical and physical factors in an ecosystem (non living) for example: temperature, moisture, salininty, soil type, light, air
limiting factors definition
factors that limit the growth of populations. they will slow the growth of a population as it approaches the carrying capacity of the system
limiting factors example
for plants: lights, nutrients, water, carbon dioxide, and temperature.
for animals: space, food, mates, nesting sites, and water.
define predetation
when one animal (or occasionally a plant) hunts and eats another organism
define herbivory
an organism that feeds off of plants. type of predation
define parasitism
a symbiotic relationship in which one species benefits at the expense of another
define mutualism
A type of symbiotic relationship in which both species benefit from the relationship.
define disease
a particular abnormal condition, a disorder of a structure or function, that affects part or all of an organism. includes organisms such as viruses, bacteria, fungi and parasites that cause disease.
define competition
the demand by individuals for limited enviornmental resources
within species: intraspecific competition
between different species: interspecific competition
define symbiosis
species live together which can include parasitism, mutualism, and commensalism.
Density-dependent factors
Factors that lower the birth rate or raise the death rate as a population grows in size. They are negative feedback mechanisms leading to the stability or regulation of the population.
When prey increases so does the predator, but when this occurs the prey decreases and then again the predators decrease too causing the prey to increase again.
Density-independent factors
Factors that affect a population disregarding population density
Factors which regulate population size can be divided into either INTERNAL or EXTERNAL
Internal: fertility rates, territory sizes
External: predation, pressure, parasitism
Ways humans can cause population growth
- increase available resources
- reduce competition
- reduce pressure from predators
- introduce animals to new areas
Ways humans decline population
- change environment, cause habitat disruption
- change the biological environment by introducing new species
- cause secondary extinctions
- overkill
define population
a group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding.
Factors affecting population size
- natality
- mortality
- migration (immigration or emigration)
Define/describe s curve
when a graph of population growth is plotted against time.
it shows initial rapid growth (exponential growth), but then slows down as the carrying capacity is reached.
4 stages:
1. lag phase: pop numbers are low leading to low birth rates
2. exponential growth phase: pop grows at an increasingly rapid rate
3. transitional phase: pop growth slows down considerably although continuing to grow
4. stationary phase: pop growth stabilises (graph flattens) and then pop fluctuates around a level that represents the carrying capacity
Define/describe j curve
exponential growth is an increasing or accelerating rate of growth.
growth is initially slow, but becomes increasingly rapid and does not slow down as population increases.
Explain the concepts of limiting factors and carrying capacity in the context of population growth
Populations have an upper level or exent to numbers that can be sustained in a given enviornment - carrying capacity. The carrying capacity represents the population size at which enviornmental limiting factors limit further population growth. The CC is affected by various limiting factors including the availability of food and water, territorial space, predetation, disease and availability of mates
Explain population growth curves in terms of numbers and rates
- Rapid increase in population growth due to high natality exceeding mortality, with abundant resources and few predators or diseases.
- Growth begins to slow as resources diminish, and the mortality rate rises due to increased competition, predators, and diseases.
- Population size stabilizes as natality equals mortality, influenced by resource scarcity and other limiting factors, maintaining a balance around the environment’s carrying capacity.
define carrying capacity
the maximum number of individuals of species that can be sustained by an environment. it represents the population size at which environmental limiting factors limit further population growth.
compare/ contrast S versus J curves
COMPARE
- Both curves show how populations grow and reach a carrying capacity
CONTRAST
- The S-curve occurs in a limited environment, while the J-curve occurs in an unlimited environment
- The S-curve represents logistic growth, while the J-curve represents exponential growth
- The S-curve eventually levels off at the carrying capacity, while the J-curve continues to increase until a limiting factor is encountered
- The S-curve is more common in nature, while the J-curve is less common and is often observed in laboratory conditions
