Evolution and Diversity

What is the primary goal of evolutionary biology?

To understand how life evolved and diversified over time.

What is a phylogenetic tree used for?

To depict evolutionary relationships among organisms.

What are the three types of body cavities used to classify animals?

Acoelomate (none), pseudocoelomate (partially lined), and coelomate (fully lined).

What are Coelomata?

Animals with a true body cavity fully lined by mesoderm.

What is the significance of Ecdysozoa?

A clade including molting animals like arthropods and nematodes, redefining phylogenetic relationships.

What challenges the idea of objective biological knowledge?

The "tyranny of experts" and controversies around classification and evolutionary history.

What concept is highlighted by the phrase "wisdom of the crowd"?

The potential for collaborative platforms like Wikipedia to contribute valuable knowledge.

Why is biology described as comparative?

Because it draws conclusions about organisms by comparing traits, genes, and evolutionary history.

What is the educational purpose of the Wiki project in this course?

To research, write, and communicate scientific information about a species, reinforcing concepts of evolution and diversity.

Why should you critically evaluate AI-generated content in scientific work?

AI can make confident but incorrect claims; always fact-check and cite reliable sources.

What is a cladogram?

A tree that shows relationships based on shared derived traits but does not represent time or amount of change.

What is a phylogram?

A tree that shows evolutionary relationships and the amount of change along each branch.

What is a dendrogram?

A tree that incorporates both relationships and evolutionary time.

What is a synapomorphy?

A shared derived trait that unites a group of organisms; essential for inferring evolutionary relationships.

What is parsimony in phylogenetics?

The principle that the simplest explanation, or tree with the fewest evolutionary changes, is preferred.

What is an autapomorphy?

A unique trait to a single species; it tells us nothing about relationships to others.

How is an outgroup used in tree-building?

To polarise characters—it helps determine which traits are primitive versus derived.

What is a paraphyletic group?

A group that includes a common ancestor but not all of its descendants (e.g., "fish").

What distinguishes a clade from a grade?

A clade is monophyletic (one ancestor + all descendants); a grade is often paraphyletic and based on level of organization.

What is the key feature of cladistics?

Grouping organisms solely based on shared derived traits (synapomorphies) and constructing trees using parsimony.

What is a molecular phylogeny?

An evolutionary tree based on DNA, RNA, or protein sequence data.

What is the molecular clock hypothesis?

The idea that genetic mutations accumulate at a relatively constant rate, allowing estimation of divergence times.

Why are molecular phylogenies powerful?

They allow us to reconstruct evolutionary relationships across all timescales, from viruses to vertebrates.

What is sequence saturation?

When multiple mutations occur at the same site, masking the true number of changes over time.

How can scientists reduce the effects of saturation?

Use different genes, model DNA evolution, or use alternative molecular data types.

What is the transition/transversion ratio?

A measure comparing two types of nucleotide substitutions; transitions (e.g. A↔G) are more common than transversions (e.g. A↔T).

What is long branch attraction?

A phylogenetic error where rapidly evolving lineages are incorrectly grouped together.

How can convergent evolution affect molecular trees?

Different species can independently evolve similar molecular features, misleading tree reconstruction.

Why is molecular data limited for extinct species?

DNA decays rapidly, with a half-life that limits retrieval beyond ~6.8 million years under ideal conditions.

What is one advantage of molecular data over morphological data?

Molecular data is less subjective and often provides clearer signals of evolutionary relationships, especially in “hard-to-place” species.

What principle is commonly used to reconstruct ancestral traits?

Parsimony – choosing the tree with the fewest evolutionary changes.

What does ancestral state reconstruction aim to determine?

What extinct ancestors likely looked like or what traits they had.

How accurate is parsimony-based ancestral reconstruction?

It performs well—94% accuracy in lab-tested cases, though not perfect.

What is Dollo parsimony?

A rule that complex traits, once lost, are unlikely to be regained in evolution.

What example challenges Dollo parsimony?

Wing loss and regain in stick insects

What is the “pre-existing bias hypothesis” in swordtail fish?

Female preference for swords evolved before males had them, guiding sexual selection.

How can reconstructed ancestors be tested?

Through laboratory synthesis of ancient proteins or traits (e.g., “Jurassic Park” approach).

What does punctuated equilibrium propose?

Evolution occurs in bursts of change, not gradual, constant rates.

What is one molecular pattern of evolutionary change?

Speciational change – rapid changes during speciation events.

Why is reconstructing ancestors scientifically valuable?

It helps us test evolutionary scenarios, such as how many times a trait evolved and when.

What are the three main aspects of biodiversity often measured?

Species richness, genetic variation, and relative abundance.

What is the primary use of allele frequency data in population genetics?

to assess genetic variation within and differentiation between populations.

What molecular method uses short tandem repeats for diversity analysis?

Microsatellites – useful for detecting variation, inbreeding, and population structure.

What is a haplotype network?

A diagram showing relationships among alleles, with branch lengths reflecting differences and node sizes indicating abundance.

What is the key benefit of PCR (polymerase chain reaction) in molecular diversity?

Amplifies targeted DNA regions, enabling analysis even from small or degraded samples.

What is a SNP (single nucleotide polymorphism)?

A single base pair variation used to detect fine-scale genetic differences and selection.

What is nucleotide diversity?

A measure of genetic variation at the DNA sequence level within a population.

What does a genetic distance matrix represent?

Pairwise differences in allele frequencies between populations, indicating genetic similarity or divergence.

What do metagenomic methods study?

DNA from environmental or community samples to assess taxonomic and functional diversity (e.g. microbiomes).

What was a key conclusion from the gorilla oral microbiome case study?

Ecology, not just host phylogeny, shapes microbial diversity—Mountain gorillas had distinct microbiomes adapted to high elevation.

What is a functional trait?

A measurable feature of an organism (e.g. morphology, behavior) that influences its fitness and ecological role.

What defines a functional group?

A set of species that perform similar roles in an ecosystem, often sharing similar traits.

What is the difference between functional diversity and functional redundancy?

Functional diversity = species perform different functions; redundancy = species perform similar functions.

What does the BIODEPTH experiment study?

The relationship between biodiversity and ecosystem functioning (BEF) across multiple European sites.

What metric is commonly used to measure ecosystem function in BIODEPTH?

Primary productivity, often measured as aboveground biomass.

What does the complementarity hypothesis suggest?

Different species use different resources, enhancing overall ecosystem productivity.

What does the facilitation hypothesis state?

Some species positively affect others, improving resource use and boosting ecosystem performance.

What is the selection effect hypothesis?

More diverse communities have a higher chance of containing a highly productive species.

What did the BIODEPTH and Cedar Creek experiments conclude?

Greater species richness leads to higher ecosystem productivity and function over time

Why is biodiversity important for ecosystem services?

It enhances carbon sequestration, soil stability, and resilience, especially when interacting with environmental factors like soil and hydrology.

What is the difference between taxonomy and systematics?

Taxonomy is the discovery and naming of species; systematics studies relationships between species.

Why is accurate taxonomy important?

Misidentifying species can have serious consequences (e.g., conservation errors, military mistakes like WWII “bat bomb” project).

What is the current estimate of described species?

Approximately 1.4–1.8 million, but real estimates range from 5 to 30 million.

What are the challenges in describing a new species?

Requires access to collections, detailed anatomy, a Latin name, diagnosis, and a type specimen.

What is DNA barcoding?

A technique that uses a short DNA sequence (e.g., COI gene) to identify and distinguish species.

What did DNA studies reveal about Amazonian frogs?

60 named species were genetically 129—showing hidden diversity.

How can DNA barcoding help conservation?

Identifies illegally traded species (e.g., whale meat), and clarifies which species are at risk.

What does EDGE stand for?

Evolutionarily Distinct and Globally Endangered – prioritizing unique species with few close relatives.

Why are some lineages more valuable for conservation?

They are evolutionarily distinct, meaning they represent long, unique evolutionary histories (e.g., tuatara)

What is the consequence of declining taxonomists?

Slower species identification and conservation, especially in diverse and understudied groups like insects.

Why is biodiversity important for conservation?

It helps maintain ecosystem function, genetic health, and supports adaptive potential against environmental change.

What three types of diversity are most relevant to conservation planning?

Molecular, taxonomic, and functional diversity.

What does inbreeding depression refer to?

Reduced fitness in offspring due to mating between close relatives, exposing harmful recessive alleles.

What paradox challenges the preference for outbreeding in conservation?

Many species persist with high inbreeding, sometimes leading to local adaptation or purging of harmful mutations.

In the African wild dog case study, what did genetics reveal about “extinct” populations?

Recolonizing individuals were genetically identical to the supposedly extinct population—supporting dispersal corridors.

What is the Evolutionarily Significant Unit (ESU) concept?

A conservation unit based on genetic distinctiveness, even if not formally recognized as a species.

What was the finding of the giraffe DNA study?

There are four genetically distinct giraffe species, not one, with implications for conservation priorities.

What ecosystem role do wildebeest play in the Serengeti?

They’re a keystone species—their population changes affect vegetation, predators, fire dynamics, and disease vectors.

What conservation lesson came from the Rinderpest vaccination?

Eradicating disease in livestock boosted wildebeest numbers, altering entire ecosystem structure and function.

Why is a functional ecosystem approach essential in conservation?

Because changes in one species or process (e.g. fire, migration) can cascade and reshape entire ecosystems.

What is the core formula behind studying evolutionary change?

Amount of evolution = rate × time

What is a rapid radiation?

A burst of fast evolutionary diversification in a short time, such as with Hawaiian honeycreepers.

How can we estimate the age of lineages?

Using fossils, biogeography, and host-parasite associations.

What problem arises with relying solely on the fossil record?

It may be incomplete, leading to underestimation of lineage ages.

What is the molecular clock hypothesis?

Assumes constant rates of molecular evolution to estimate divergence times.

What does cospeciation refer to?

Parallel speciation of hosts and parasites, suggesting linked evolutionary histories.

What is punctuated equilibrium?

Evolution characterized by long stasis periods interrupted by rapid change

What is the evidence for speciational change in molecular evolution?

Some studies show increased molecular change occurs during speciation events.

What is a limitation of using morphology to study rates of evolution?

Morphological change can be decoupled from molecular evolution (e.g. coelacanths show genetic but not morphological change).

What is an example of a “living fossil” showing evolutionary stasis?

The coelacanth, virtually unchanged morphologically for over 65 million years.

What is vicariance?

When species distributions are split by geological events like continental drift or mountain formation.

What is an example of vicariance?

The breakup of Gondwana explains the separation of ratites (flightless birds) across the Southern Hemisphere.

What is stream capture, and how does it affect evolution?

A river changes course and captures another’s drainage, isolating populations and driving genetic divergence (e.g. NZ Galaxias fish).

How do islands support rapid diversification?

Their isolation and sequential formation (e.g. Hawaiian Drosophila) promote adaptive radiation.

What does Oligocene drowning refer to?

A period when much of New Zealand was submerged, isolating species and contributing to its distinct biodiversity.

What are hotspots, in evolutionary terms?

Volcanic regions where new islands form, enabling sequential colonization and diversification (e.g. Galapagos, Hawaii).

What are disjunctions in biogeography?

Species with related forms in distant places, often due to continental drift or dispersal.

How does molecular divergence support biogeographic history?

It reveals timing of separations and confirms patterns predicted by fossil and geological data (e.g. New Zealand birds).

What is the key insight from this lecture?

Earth’s geological dynamics (e.g. continental drift, rivers, islands) are central to understanding macroevolutionary patterns.