Biology Unit 3 Topic 1: Describing Biodiversity and Populations

Flashcards covering vocabulary terms for Biology Unit 3 Topic 1, including biodiversity concepts, species definitions, classification systems, sampling techniques, and population growth dynamics.

Genetic Diversity

The variation in DNA within a species, including different genes and alleles, which provides the raw material for adaptation and survival under changing conditions.

Biological Species Concept

A concept proposed by Ernest Mayr in $1942$ defining a species as a group of organisms where individuals are able to interbreed to produce fertile offspring in the wild.

Binomial Nomenclature

The formal system of naming species developed by Carl von Linne, using a two-word Latin scientific name consisting of the capitalised genus name followed by the lowercase specific species name.

Dichotomous Key

A tool used to identify unknown organisms by following a sequence of yes/no decisions or paired contrasting statements about observable physical traits.

Lincoln Index

A mathematical formula ($N = \frac{M \times n}{m}$) used to estimate the population size of mobile animals using mark-recapture data.

Species Richness

A measure of biodiversity defined as the total number of different species present in a specific sample or area, without taking individual abundances into account.

Species Evenness

A measure of biodiversity expressing the relative abundance or distribution of individual organisms among the different species present in an area.

Percentage Cover

An estimate of the percentage area of a quadrat that a given species occupies, typically used for stationary organisms like grasses.

Percentage Frequency

A measure of the probability that a particular species will appear in any randomly selected sample quadrat within an ecosystem.

Simpson's Diversity Index

A quantitative measure of biodiversity calculated as $SDI = 1 - \frac{\sum n(n-1)}{N(N-1)}$, where a value closer to $1$ indicates higher diversity.

Stratified Sampling

A statistical sampling method where an ecosystem is divided into homogeneous sub-groups or strata based on habitat zones before taking random samples within each stratum.

Belt Transect

A sampling technique where quadrats are placed along a transect line at marked points to estimate the distribution and percentage cover of organisms across an environmental gradient.

Biotic Factors

The living components of an ecosystem that influence species distribution and abundance, including food availability, competition, predation, and disease.

Abiotic Factors

The non-living physical and chemical components of an ecosystem that affect species distribution, including space, shelter, water availability, nutrients, and temperature.

Microhabitat

A small, specific area within a larger habitat that possesses distinct environmental conditions, such as the underside of a rock or tree bark.

Specht's Classification System

A system used to classify and name ecosystems based on the dominant vegetation type, its height, and the percentage of foliage cover shading the ground.

Exponential Growth

A model of rapid population growth without limits that occurs under ideal conditions with unlimited resources, producing a J-shaped curve on a graph.

Logistic Growth

A population growth model where growth is rapid initially but slows down and levels off as the population reaches the environment's carrying capacity, producing an S-shaped curve.

K-strategists

Organisms that produce few offspring, invest high parental care, have long lifespans, and maintain stable populations near carrying capacity following a logistic growth curve.

r-strategists

Organisms that produce large numbers of offspring with little or no parental care, have short lifespans, and experience boom-and-bust population cycles following an exponential growth curve.