Evolution and Ecology

Ecology and Evolution

• Evolution is defined as a change in gene frequency or allele over time.
• Evolution only acts at the population level.
• Natural selection is a mechanism for evolution.
• In natural selection, the fittest organisms survive and pass on their genetics, while the least successful do not.
• An ecological niche is the role a species plays in a community and the set of environmental factors determining its distribution.
• Habitat refers to the place or set of environmental conditions where a particular organism lives.
• Carrying capacity is the population size a specific area can support without depleting available resources.
• A population crash is a rapid decline in population size to below the carrying capacity.
• Overshoot occurs when a population exceeds the carrying capacity, often leading to a population crash.
• Predation involves one organism (predator) hunting, killing, and eating another (prey), playing a key role in ecosystem balance.
• Generalist species have a broad niche, such as brown rats, allowing them to live in many environments.
• Specialist species have a narrow niche, exemplified by the giant panda.
• Indicator species, or bioindicators, have tolerance limits that reflect the environmental conditions, indicating either positive or negative conditions.
• Tolerance limits define the range of conditions within which a species can survive.

Population Dynamics

• R-selected species exhibit rapid reproduction and population growth in unstable environments.
• K-selected species prioritize survival and competition in stable, resource-limited environments.
• Fire ecology studies the role of fire in ecosystems.
• Logistic growth (S-curve) describes a population that grows rapidly at first but slows down as it approaches its carrying capacity, forming an S-shape when resources become limited.
• Exponential growth (J-curve) occurs when a population increases rapidly without limits, forming a J-shape curve and leading to larger increases as the population expands under abundant resources.
• Population crash (dieback) is a rapid population decline after exceeding the carrying capacity, typically happening when resources are highly limited.
• Overshoot is when a population temporarily exceeds the ecosystem's carrying capacity, leading to overuse of resources, environmental degradation, and potential population crashes.
• Density-dependent factors cause the growth rate to depend on population density, intensifying as population size increases through mechanisms like logistic growth, disease rates, physiological stress, competition, and predation.
• Biotic population control regulates population size through interactions between living organisms, including predation, competition, and disease.
• R-selected species rely on a high reproductive rate to overcome high offspring mortality, often with little or no prenatal care.
• K-selected species have few offspring, slower growth as they approach carrying capacity, and more extensive parental care.
• Type 1 survivorship describes when most individuals die later in life.
• Type 2 survivorship describes when individuals die at a uniform rate.
• Type 3 survivorship describes when most individuals die at a young age.
• Predator-prey oscillations occur when predator and prey populations fluctuate in response to each other.
• Age structure graphs, or population pyramids, visually represent the distribution of ages within a population.
• Thomas Malthus's population theory posits that unchecked population growth would outstrip food production, leading to starvation, disease, and misery, suggesting population control as a solution.
• Demography is the study of human populations, including births, deaths, and growth rates.
• Total fertility rate (TFR) is the average number of children a woman is expected to have in her lifetime.
• Crude birth rate is the number of live births per 1,000 people per year.
• Crude death rate is the number of deaths per 1,000 people per year.
• Life expectancy is the average number of years a newborn is expected to live.
• Life span is the oldest age to which members of a species survive.

Population Models and Ecology

• Demographic Transition Model, proposed by Thomas Malthus, suggests human population growth is exponential while food supply grows arithmetically, leading to resource shortages.
• Karl Marx's population perspective attributes population growth to poverty and social inequality rather than population size itself causing resource shortages.
• Restoration ecology involves scientific efforts to repair or reconstruct ecosystems damaged or degraded.
• Bioremediation is the use of living organisms, such as bacteria, plants, or fungi, to clean up pollution in soil, water, or air.
• Remediation encompasses the use of chemical, physical, or biological methods to remove pollution from an environment.
• Reclamation is the process of restoring severely degraded lands to functional use, often after mining or industrial activities.
• Rehabilitation is the partial restoration of an ecosystem to a useful or stable condition, not necessarily its original state.
• Reintroduction involves bringing native species back to areas where they have been extirpated.
• Prescribed burns involve the controlled use of fire to manage and restore ecosystems like savannas and prairies.
• Artificial wetlands are man-made wetlands used for treating sewage, stormwater, runoff, and industrial cooling.
• Ecosystem services are benefits provided by ecosystems, including clean water, air, habitat, and flood control.
• Tolerance limits define the range of environmental conditions (temperature, salinity, etc.) within which a species can survive.
• Biotic factors are living components that tend to be density-dependent.
• Abiotic factors are non-living components that tend to be density-independent.
• The first step in ecological restoration is to remove the source of harm or damage.
• Aldo Leopold is considered the father of restoration ecology, associated with initiatives such as planting 6,000 plants per year.
• Carrying capacity represents the maximum population size that an environment can sustain.
• Survivorship curves (types 1, 2, and 3) illustrate the pattern of survival in a population, with type 1 characterized by high care with offspring.
• R-selected species, like rats, reproduce quickly, have short life spans and expectancies, and provide low care for offspring.
• Thomas Malthus warned that running out of resources would lead to famine and misery.
• The world population reached 1 billion in 1800.
• The Demographic Transition Model suggests that birth rates and death rates change as a population develops, eventually reaching an equilibrium.
• Karl Marx argued that population growth is driven by social inequality.
• An S-shaped curve indicates logistic growth.
• Rehabilitation includes rebuilding a community, but not necessarily to its original condition.
• Habitat is where an organism lives.
• Ecological niche describes the specific conditions a species lives in.
• Indicator species provide indications about their environment.
• Wetlands serve as a primary source of food and are highly productive.
• Savannas benefit from prescribed burns.
• Keystone species, such as otters, play a critical role in an ecosystem.
• Emigration describes when individuals leave a population.
• Predator-prey oscillations are when a population of prey increases, the predator population increases, and then the populations decrease in a wave.
• Dieback is a population crash.
• If an organism eats roadkill then it’s a generalist species.
• Primary succession occurs on bare rock.
• Secondary succession occurs on an environment after a natural event.
• Wetlands can be used for recreation, such as kayaking.
• When a population is declining, the fertility rate is low and below replacement levels.