Untitled Flashcard Set

Q: What is genetic diversity?
A: The variety of alleles and genes within a species (or population), arising from mutation, recombination, and gene flow. It's the raw material for adaptation and evolution — higher genetic diversity means a population is more likely to contain individuals able to survive environmental change.

Q: What is species diversity?
A: The variety of species within a given area or ecosystem, made up of two components: species richness (the number of different species present) and species evenness (how equally individuals are distributed among those species).

Q: What is ecosystem diversity?
A: The variety of different ecosystems (e.g. forests, wetlands, coral reefs, grasslands) within a region or on Earth, including the variety of habitats, communities, and ecological processes that occur across them.

Q: Why do we need all three levels (genetic, species, ecosystem) to properly describe biodiversity?
A: Because they operate at different scales and one doesn't guarantee the others — an area could have many species (high species diversity) but low genetic diversity within each population, or many ecosystems but few unique species. A full picture of biodiversity requires assessing all three.

BIOLOGICAL SPECIES CONCEPT

Q: What is the biological species concept?
A: A species is defined as a group of organisms that can interbreed in nature and produce fertile, viable offspring, and that are reproductively isolated from other such groups.

Q: What are the limitations of the biological species concept?
A: It cannot be applied to: (1) asexually reproducing organisms (e.g. bacteria, many fungi); (2) fossils, since we can't test if extinct organisms could interbreed; (3) ring species, where neighbouring populations interbreed but the two end populations cannot; (4) organisms that hybridise across "species" lines (e.g. some plants, ligers/tigons); and (5) it's impractical to directly test interbreeding for most wild populations.

Q: Why is the ring species problem a challenge to the biological species concept?
A: In a ring species, each neighbouring population can interbreed with the next along a geographic ring, but the two populations at the ends of the ring — where the ring closes — cannot interbreed. This makes it impossible to draw a clean line about where one species ends and another begins.

LINNAEAN CLASSIFICATION

Q: List the major taxa of the Linnaean classification system, from broadest to most specific.
A: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species (mnemonic: "Dear King Philip Came Over For Good Soup").

Q: How does binomial nomenclature name a species?
A: Each species gets a two-part Latin name: Genus (capitalised) + species (lowercase), both italicised (or underlined if handwritten), e.g. Homo sapiens. This gives every species a unique, universally recognised scientific name regardless of language.

Q: How is the Linnaean system used to classify organisms into these taxa?
A: Organisms are grouped based on shared physical, structural, and increasingly genetic/molecular characteristics. Organisms sharing the most features are grouped into the smallest taxon (species), and as you move up the hierarchy, groups become broader and are based on more general shared traits (e.g. all organisms in a Class share fewer specific features than those in a Genus).

Q: Why is a standardised naming system like this useful to biologists worldwide?
A: It avoids confusion from common names (which vary by language/region and can refer to different organisms), allows unambiguous communication between scientists globally, and reflects evolutionary relationships between organisms.

DICHOTOMOUS KEYS

Q: What is a dichotomous key and how does it work?
A: A tool for identifying organisms using a series of paired (either/or) statements about observable characteristics. At each step you choose the statement that matches the organism, which leads either to another pair of statements or to the identification of the organism.

Q: What features make a good dichotomous key?
A: Statements should be mutually exclusive (clearly either/or, no overlap), based on easily observable and consistent features, use precise/quantifiable descriptions (e.g. "leaves >5cm" rather than "large leaves"), and proceed logically from general to specific features.

LINCOLN INDEX (CAPTURE-RECAPTURE)

Q: State the Lincoln Index formula and define each term.
A: N = (M × n) / m, where N = estimated total population size, M = number of individuals marked and released in the first capture, n = total number caught in the second capture, m = number of marked individuals recaptured in the second capture.

Q: What assumptions underlie the Lincoln Index?
A: (1) The marked population mixes randomly back into the whole population; (2) no births, deaths, immigration or emigration occur between the two sampling events (closed population); (3) marking doesn't affect survival or behaviour/catchability; (4) marks are not lost and remain identifiable; (5) all individuals have an equal chance of being captured.

Q: A population is sampled: 40 individuals are marked and released; a second sample of 60 individuals is caught, and 12 of them are marked. Estimate the population size.
A: N = (M × n)/m = (40 × 60)/12 = 200 individuals.

Q: What sources of error can make a Lincoln Index estimate inaccurate?
A: Marked individuals becoming more/less catchable (trap-happy or trap-shy behaviour), marks fading or falling off, insufficient time for marked animals to redistribute randomly, and population changes (births/deaths/migration) between captures.

MEASURES OF SPECIES DIVERSITY

Q: Define species richness.
A: The total number of different species present in a given area, without regard to how many individuals of each species there are.

Q: Define species evenness (relative abundance).
A: A measure of how equally individuals are distributed among the species present. High evenness = individuals spread roughly equally across species; low evenness = one or a few species dominate in numbers.

Q: How is percentage cover calculated and when is it used?
A: Percentage cover = (area covered by a species / total area of the quadrat) × 100. It's used for species where individual counting is impractical, like grasses, mosses, or spreading plants — usually estimated visually or with a point quadrat.

Q: How is percentage frequency calculated and when is it used?
A: Percentage frequency = (number of quadrats in which the species occurs / total number of quadrats sampled) × 100. It shows how widely distributed a species is across a sampling area, rather than its abundance in any one spot.

Q: Write the formula for Simpson's Diversity Index and explain what it measures.
A: SDI = 1 − [Σn(n−1)] / [N(N−1)], where n = number of individuals of a particular species, and N = total number of individuals of all species. It combines richness and evenness into a single value between 0 and 1 — values closer to 1 indicate higher diversity (more species, more evenly distributed); values closer to 0 indicate lower diversity (dominated by few species).

Q: A sample has 3 species: Species A (n=10), Species B (n=6), Species C (n=4). Calculate Simpson's Diversity Index.
A: N = 20. Σn(n−1) = 10(9) + 6(5) + 4(3) = 90 + 30 + 12 = 132. N(N−1) = 20(19) = 380. SDI = 1 − (132/380) = 1 − 0.347 = 0.65 (moderately high diversity).

SAMPLING METHODS AND TECHNIQUES

Q: Describe random sampling and when it's used.
A: Sample points/locations are chosen using a random method (e.g. random number generator on a grid), giving every point equal chance of selection. Used when the habitat is fairly uniform, to avoid unconscious bias in site selection.

Q: Describe systematic sampling and when it's used.
A: Samples are taken at regular, fixed intervals along a line or grid (e.g. every 5 metres). Used when investigating a gradient or pattern across an area (e.g. distance from a water source, a shoreline, or a shaded-to-sunny transition).

Q: Describe stratified sampling and when it's used.
A: The area is first divided into distinct sub-habitats/zones (strata) based on an obvious difference (e.g. shaded vs open, wet vs dry), and then random or systematic sampling is carried out within each stratum, often proportional to its area. Used when the habitat is not uniform and different zones need fair representation.

Q: What is a quadrat and what is it used for?
A: A square frame of known area (e.g. 1m × 1m) placed on the ground to sample a defined area — used to count individuals, estimate percentage cover, or measure percentage frequency for slow-moving or stationary organisms (plants, sessile animals).

Q: What is a line transect?
A: A measuring tape/line laid across a habitat (often along an environmental gradient); species touching or crossing the line at set intervals are recorded, showing how species distribution changes along that line.

Q: What is a belt transect?
A: Similar to a line transect but uses a band of a set width (e.g. by placing quadrats at intervals along the line), giving a 2D strip of data rather than a single line — allowing estimation of abundance/cover, not just presence, along the gradient.

Q: What is capture-recapture and what is it used for?
A: A technique (using the Lincoln Index) for estimating population size of mobile animals: individuals are caught, marked, and released, then a second sample is taken later and the proportion of marked individuals is used to estimate total population size.

Q: List strategies to minimise bias in sampling.
A: Use an adequate sample size and number of samples (statistically representative); use random-number generators to select quadrat/sample locations rather than personal choice; set clear, consistent counting criteria (e.g. only count if >50% of the organism is inside the quadrat); calibrate equipment before use and record its precision/limitations; and repeat sampling to check reliability.

Q: Why does increasing the number and size of samples improve reliability?
A: Larger/more samples reduce the impact of random natural variation and better represent the true diversity/distribution of the whole area, reducing the chance that an unusual patch skews the result.

BIOTIC AND ABIOTIC FACTORS ON DISTRIBUTION/ABUNDANCE

Q: How does food availability affect species distribution and abundance?
A: Species will be more abundant and widely distributed where food is plentiful; low food availability limits population size (via starvation, reduced reproduction) and can restrict a species to areas where food sources are concentrated.

Q: How does competition for resources affect distribution and abundance?
A: Competition (for food, space, light, mates) between individuals of the same species (intraspecific) or different species (interspecific) can limit population size and exclude species from habitats where a stronger competitor dominates (competitive exclusion), affecting where species are found.

Q: How does predation affect distribution and abundance?
A: High predator numbers or efficiency reduces prey population size and can restrict prey to habitats offering more shelter/refuge from predators; predator and prey populations are often linked in cyclical abundance patterns.

Q: How does disease affect distribution and abundance?
A: Disease can rapidly reduce population size (especially in dense populations, where transmission is easier), and can restrict a species' range if disease prevalence is higher in certain areas or climates.

Q: How does space (as an abiotic factor) affect distribution and abundance?
A: Limited physical space restricts how many individuals/territories an area can support, driving territorial or dispersal behaviour and setting an upper limit on population density.

Q: How does shelter affect distribution and abundance?
A: Availability of shelter (from predators, weather, or to nest/breed) determines which areas are habitable; species will be more abundant where adequate shelter is available.

Q: How does availability of water affect distribution and abundance?
A: Water availability is essential for survival and reproduction; species distribution often closely tracks water sources (rivers, waterholes), especially in arid ecosystems.

Q: How do nutrients (as an abiotic factor) affect distribution and abundance?
A: Soil or water nutrient levels (e.g. nitrogen, phosphorus) determine primary productivity — areas with poor nutrients support fewer plants and, in turn, fewer organisms at higher trophic levels.

Q: How do environmental conditions (temperature, light, pH, etc.) affect distribution and abundance?
A: Each species has a tolerance range for factors like temperature, light intensity, salinity, and pH; species are only found where conditions fall within their tolerance range, and abundance peaks near their optimum conditions.

HABITATS, MICROHABITATS AND DISTRIBUTION PATTERNS

Q: What is a microhabitat?
A: A small-scale, localised environment within a larger habitat that has distinct conditions (e.g. under a log, in leaf litter, a rock crevice, a tree hollow) — species distribution can vary greatly even within what looks like one uniform habitat.

Q: Why do microhabitats matter for sampling design?
A: If species are concentrated in specific microhabitats, a sampling method that ignores this (e.g. random sampling across a whole large area) may miss or under-represent them — stratified sampling that accounts for microhabitat zones gives more valid and reliable results.

Q: Describe uniform (regular) distribution and give an example of when it occurs.
A: Individuals are spaced roughly evenly apart, often due to competition for resources or territorial behaviour (e.g. penguins nesting, or trees releasing allelopathic chemicals to space out root systems).

Q: Describe random distribution and give an example of when it occurs.
A: Individuals are positioned with no predictable pattern, position of one individual is independent of others — occurs when resources are abundant and evenly available and there's no strong social/competitive interaction (e.g. dandelions in a uniform field, spread by wind).

Q: Describe clumped (aggregated) distribution and give an example of when it occurs.
A: Individuals are grouped in patches, often around a resource (food, water, shelter) or due to social behaviour (herding, schooling) or localised reproduction (seed dispersal near parent plant). This is the most common distribution pattern in nature.

Q: Why does clumped distribution make random sampling less reliable, and what's a better approach?
A: Random samples might, by chance, mostly fall in patches (overestimating abundance) or entirely miss them (underestimating abundance) — stratified sampling (identifying patches/zones first) generally gives more valid and reliable results for clumped distributions.

INTERPRETING ABIOTIC FACTOR EXPERIMENTS

Q: When interpreting data from an experiment on abiotic factors and biodiversity, what should you look for?
A: Trends/patterns in the data (e.g. does diversity/abundance increase or decrease as the abiotic factor changes?), correlations between the factor and each diversity measure, any threshold or optimum values, and whether the pattern is consistent across replicates — while being careful to describe correlation without automatically claiming causation unless the experimental design supports it.

Q: What limitations should you consider when interpreting such data?
A: Sample size, whether other variables were controlled, whether the relationship might be correlational rather than causal, the range of the abiotic factor tested (results may not extend beyond it), and potential confounding factors (e.g. other abiotic/biotic variables changing alongside the one measured).

CLASSIFYING ECOSYSTEMS: SPECHT AND HOLDRIDGE

Q: What is Specht's classification system based on?
A: It classifies Australian vegetation communities based on the growth form (structure) of the tallest/dominant stratum (e.g. tree, shrub, herb) and its percentage foliage (canopy) cover — giving categories like closed forest, open forest, woodland, open woodland, and various shrubland/heath/grassland categories with decreasing cover.

Q: What is the Holdridge Life Zone classification scheme based on?
A: It classifies world ecosystems ("life zones") based on three climatic variables: mean annual biotemperature (temperature adjusted so values below 0°C count as 0), mean annual precipitation, and potential evapotranspiration ratio (PET ratio — how much moisture could evaporate vs. what falls as rain), arranged on a triangular diagram to predict vegetation type (e.g. rainforest, desert, tundra).

Q: How would you use these systems to interpret ecosystem data?
A: For Specht: identify the dominant growth form present and measure/estimate its percentage foliage cover, then match to the corresponding category (e.g. >70% cover with trees = closed forest). For Holdridge: take temperature and precipitation data, calculate the PET ratio, and locate the point on the Holdridge triangle to determine the predicted life zone/biome.

POPULATION GROWTH MODELS

Q: Describe exponential growth (J-curve) and the conditions under which it occurs.
A: Population size increases at an accelerating rate over time, producing a J-shaped curve, because growth rate is proportional to population size and resources are (initially) unlimited. Occurs when a population colonises a new area or resources are abundant with few limiting factors (e.g. early stage of population growth, or invasive species in a new environment).

Q: Describe logistic growth (S-curve) and the phases involved.
A: Population grows exponentially at first, then growth rate slows as resources become limiting, and the population levels off at the carrying capacity (K) — producing an S-shaped curve. Phases: lag phase (slow initial growth), exponential/log phase (rapid growth), and plateau/stationary phase (growth rate ≈ 0, population stable around K).

Q: What is carrying capacity (K)?
A: The maximum population size that an environment can sustainably support given available resources (food, space, water, etc.) without long-term degradation of the habitat.

Q: Why does logistic growth eventually level off while exponential growth doesn't?
A: In logistic growth, density-dependent factors (competition, food scarcity, disease, predation, waste build-up) intensify as population size increases, slowing birth rates and/or raising death rates until they balance at K. Exponential growth assumes no such limiting factors ever kick in.

R- AND K-STRATEGISTS

Q: What are r-strategists? Describe their reproductive strategy and growth curve.
A: Species that prioritise rapid reproduction: many offspring, early maturity, short lifespan, little/no parental care, and high mortality rates in offspring. They follow a J-curve (exponential growth), thrive in unstable/unpredictable environments, and are good colonisers (e.g. insects, weeds, bacteria, mice).

Q: What are K-strategists? Describe their reproductive strategy and growth curve.
A: Species that prioritise quality over quantity of offspring: few offspring, later maturity, longer lifespan, significant parental care/investment, and low offspring mortality. They follow an S-curve (logistic growth), are adapted to stable environments near carrying capacity, and are typically strong competitors (e.g. elephants, whales, humans).

Q: Summarise the key differences between r- and K-strategists in a comparison.
A: r-strategists: many small offspring, no/little parental care, short generation time, boom-bust populations, thrive in disturbed/unpredictable environments, J-curve. K-strategists: few large offspring, high parental care, long generation time, stable populations near K, thrive in stable environments, S-curve.

POPULATION GROWTH RATE AND CHANGE

Q: What is the general formula for population change?
A: Population change = (Births + Immigration) − (Deaths + Emigration).

Q: A population starts at 500. Over one year: 80 births, 40 deaths, 15 individuals immigrate, and 25 emigrate. Calculate the population change and the new population size.
A: Change = (80 + 15) − (40 + 25) = 95 − 65 = +30. New population size = 500 + 30 = 530.

Q: How is population growth rate typically expressed?
A: Often as a percentage: Growth rate (%) = (Population change / Original population size) × 100. Using the example above: (30/500) × 100 = 6% growth over the year.

Q: What does a negative population change value indicate?
A: The population is declining — deaths and emigration together exceed births and immigration for that period.