Week 15 - Population dynamics, Extinction and conservation

What is exponential growth in population dynamics?

A model where population size increases rapidly without limits, defined by the equation N(t+1) = Nt + B - D.

What does the Malthusian parameter (r) indicate?

It represents the instantaneous growth rate of a population; if r > 0, the population increases; if r < 0, it declines.

What is the logistic growth model?

A model that accounts for limited resources, leading to a carrying capacity (K) where population growth slows as it approaches K.

What is carrying capacity (K)?

The maximum population size that an environment can sustain due to limited resources.

What is the Lotka-Volterra competition model?

A model that describes the dynamics of biological systems in which two species compete for the same resources.

What are population cycles?

Regular fluctuations in population size over time, often observed in species like lynx and hares.

What causes population cycles?

Factors such as predator-prey dynamics, random fluctuations, and environmental changes.

What is the difference between extirpation and extinction?

Extirpation refers to the local extinction of a species in a specific area, while extinction is the total disappearance of a species globally.

What are the five major mass extinction events?

Ordovician, Devonian, Permian, Triassic, and Cretaceous extinctions.

What is background extinction?

The normal rate of extinction that occurs over time due to natural processes.

What characterizes a mass extinction event?

A rapid loss of a significant percentage of species in a short time, typically affecting at least 60% of species.

What was the Permian extinction known for?

It was the most severe mass extinction, resulting in the loss of 75% of tetrapod genera and 90-95% of marine species.

What are the primary causes of mass extinctions?

Major temperature changes, increased volcanism, and meteor strikes.

What is the 6th mass extinction?

A current extinction event driven primarily by human activities, with extinction rates much higher than the background rate.

What evidence suggests we are in a 6th mass extinction?

Global population declines, increased extinction rates, and significant losses in biodiversity, especially among larger taxa.

What factors contribute to human-driven extinctions?

Habitat loss, introduction of invasive species, overfishing, and disease.

What is the role of amphibians in extinction studies?

Amphibians are considered bioindicators due to their sensitivity to environmental changes and high extinction risk.

What is the significance of the carrying capacity in population dynamics?

It determines the maximum population size that can be sustained by the environment, influencing growth rates.

How do predator-prey dynamics affect population cycles?

Predators and prey can oscillate in population sizes due to time lags in reproduction and resource availability.

What is the impact of human population growth on extinction rates?

As human population increases, extinction rates also rise, leading to significant biodiversity loss.

What are the consequences of logistic growth?

Population dynamics shift from density-independent to density-dependent growth as resources become limited.

What is the significance of the competition coefficient (alpha) in the Lotka-Volterra model?

It quantifies the effect of one species on another in terms of resource competition.

What is the relationship between body size and population cycling?

Species that exhibit population cycles tend to have specific body sizes and reproductive rates within a certain range.

What is the role of green initiatives in conservation?

They aim to mitigate human impact on ecosystems and promote biodiversity through sustainable practices.

What is the significance of the term 'adaptive radiation' following mass extinctions?

It refers to the rapid evolution of surviving species to fill ecological niches left vacant by extinct species.

What is the effect of habitat fragmentation on species extinction?

It leads to reduced genetic variability and increases the risk of extinction for isolated populations.

How does the introduction of disease contribute to species extinction?

New diseases can decimate populations, especially in species that lack immunity to these pathogens.