Life on Earth

Question 1

de Vos et al 2014

Answer 1

sixth great extinction
contemporary rates are 1000-10,000 times higher than the background geological record

Question 2

UN 2019

Answer 2

1/4 of species at risk of extinction

Question 3

economic importance of biodiversity

Answer 3

In UK, contributes to all sectors of the economy (gov 2024)

Question 4

Biodiversity definition

Answer 4

“The variability among all living organisms from all sources, inter alia, terrestrial, marine, and other aquatic ecosystems and the ecological diversity within species, between species and of ecosystems” (Article 2, Convention on Biological Diversity, or the Rio Convention, 1992)

Question 5

measurement of biodiversity

Answer 5

species is just one way to measure
working estimate 3.5mil-111.5mil
Uncertainties from -
Taxonomic groups, viruses, bacteria, fungi, mites, insects
Habitats and biomes, soils, tropical biomes, deep-ocean benthos
On average >15,000 new species discovered each year, most are insects

Question 6

Insect Biodiversity

Answer 6

2-20 million species, crucial to successful ecosystem functioning (pollination, food source).
Beetles have the largest amount. Panamanian rainforest (Erwin, 1998), Luehea seemannii tree, one tree had 400 different species of beetle out of the canopy, 200 living in lower limbs and trunks.

Question 7

species definition

Answer 7

Darwin did not define in origin of species (1859)
biologival species concept -
A distinct reproductive group, a population of organisms which naturally mate in the wild and produce viable offspring, which can continue to reproduce.

inter -species reproduction produces sterile hybrids.

harder to use the concept with plants - false oxlip (primrose and cowslip hybrid)

Question 8

evolutionary species concept

Answer 8

Organisms which have direct ancestor-descendant relationship, i.e. shared evolutionary history.

Determined from fossils.

Precise evolutionary history of fossils impossible to know.

Question 9

Phylogenetics

Answer 9

study of evolutionary history of life using genetics

Question 10

genotypic clusters

Answer 10

genetic advancement of morphology (identifying species based on physical characteristics).

genotypic clusters classify species based on genetic similarity

DNA revolution - can build phylogenetic trees based on data

Question 11

problems with genotypic clusters

Answer 11

Hybridisation can blur genetic boundaries, creating a continum of genetic variation rather than discrete categories (Mallet, 2008)

Question 12

species richness

Answer 12

the number of different species represented in an ecological community, landscape or region

Question 13

diversity within the plant kingdom

Answer 13

can be categorised by growth form - structural and functional traits, size, lifespan, how they grow.

Trees, herbs, epiphyte, climber

Question 14

species richness vs biodiversity

Answer 14

Biodiversity includes multiple levels of biological variation - genetic, species and ecosystem diversity

considers species eveness

functional diversity (species importance)

ecological resillience

Question 15

Biogeography history

Answer 15

Joseph banks, went on captain cooks voyage. collected species, enslaved people to do so
Alfred Wallace independently theoreticised evolution by natural selection

naming of species - most birds discovered in GS named to honour people in GN

Question 16

ecosystem services

Answer 16

benefits they provide to humanity, come from natural capital
concept popularised by millenium ecosystem assessment, 2005

provisioning (food, energy), regulating (carbon sequestration, pest control(, supporting (primary production, nutrient cycle), cultural services

Question 17

Keystone species

Answer 17

no precise definition, some species have more important effects than others

disproportionate impact in their environment

cultural keystone species

Question 18

trophic cascade

Answer 18

how predators can structure entire communities through interaction with prey - alternative to view that ecosystems are controlled by nutrient availability

top down and bottom up recognised as operating simultaneously

Question 19

Lake Guri experiment

Answer 19

1986 Dam on Caroni river, venezuela for HEP
Extensive rainforests reduced to islands, had lost up to 75% of species on smaller islands (largest had retained most)
Within 4 years, all islands had lost their top predators
Shows the principles of the Theory of Island Biogeography, that smaller islands sustain fewer species
Ecological release, fewer species competing for resources
Populations of remaining species increase and become more abundant on smaller islands
As habitat shrinks, predators are lost, leads to trophic cascade effect
Overgrazing

Question 20

wolves in yellowstone NP

Answer 20

Wolves were seen as problematic
Extapation (locally extinct) in mid-1920’s
Their pray, the elk, grew in population
They browse on trees etc., vegetation cover declined
Reintroduced wolves, decline in elks, recovered vegetation (1996)

other factors or trophic cascade? - compare age of different trees in NP, none older than 1996, recovery of alders associated with reintro.

direct (reducing numbers) or indirect (behavioural)

Grassland - lack of wolves increases productivity, herbivory stimulates root growth.

Question 21

biodiversity and ecosystem services

Answer 21

some evidence that BD is correlated with regulation of ES
lack data

Question 22

NPP

Answer 22

NPP = GPP - respiration

(GPP = total energy fixed by photosynthesis).

seasonal varitation.

oceans and land are similar - land is disproportionatley more important in terms of area.

Question 23

biome

Answer 23

• a world region compromising communities of plants and animals characterised by their adaptations to that particular climate and/or environment.

Question 24

photosynthesis

Answer 24

temp - rate increases until around 18 C, levels off
role of precipitation increases NPP irrespective of biome, once saturated NPP is unchanged

Question 25

latitudinal gradients of biodiversity

Answer 25

mammal, bird, amphibian are not congruent. species are richer at lower latitudes. not tropics, around 20 degrees is most richness

Question 26

Equilibrium explanations

Answer 26

biodiversity differences are a product of modern biological and ecological processes (holocene). Area - tropics have the greatest landmass, Temperature is fairly constant, complex topography and community of vegetation. Greater habitat diversity correlates with greater resource gradients and niche space. Stratified structures, canopies. Environmental stability, annual and geological scale. This relationship (NPP=Biodiversity) breaks down at smaller scales. Estuaries, marshes etc have very low diversities but high NPP, often dominated by a single species of plants

Question 27

historical (non-equilibrium) explanations

Answer 27

- geological legacy, Tropics have not been through repeated quaternary glaciations as the higher latitudes have. Local species in higher lats will have either gone locally extinct or migrated towards tropics.

Question 28

hotspots

Answer 28

A hotspot should already have lost 70% of its primary vegetation. Notion is contested, politics plays a role. Only considers species richness. endemism

Question 29

requirements for life

Answer 29

energy source, solvent, right conditions (temp, ph, raw mats)

Question 29

ecological tolerance

Answer 29

An organism can survive across a range of environmental conditions, ‘niche breadth’, but does the best in optimal conditions.

Question 30

Liebig (1840)

Answer 30

law of the minimum. productivity , growth or reproduction of an organism will be constrained if one or more factors fall below its limiting level.

Question 30

niche

Answer 30

- determined by habitat in which a species lives -relationship of that species to its environment and other species - related to resources A species exists in multidimensional space defined by the different physical factors affecting its abundance

Question 31

light and photosynthesis

Answer 31

approx hyperbolic response to light. Low intensity, linear increase in rate. Compression point - point at which light intensity and photosynthesis are sufficient to offset loss of energy through respiration too much light - photo-inhibition, shrinking of chloroplasts

Question 32

fundamental niche

Answer 32

entire set of optimum conditions which a species can occupy in the absence of competition (potential niche)

Question 33

realised niche

Answer 33

actual set of conditions in which a species normally lives

Question 34

competitve exclusion

Answer 34

complete competitors cannot coexist indefinitely (Grinnel, 1904) If they are competing for the same resources, then one will overcome the other, leading to extinction, or evolutionary shift towards a different ecological niche coexisting species must have different niches

Question 35

cambridge

Answer 35

high species richness - habitat variety, lands under arable cultivation, river cam, built areas, intensity of recording undervaluation of urban ecology

Question 36

vegetation succession

Answer 36

implies progressive sequence through time/space one of earliest ecological concepts (Clements, 1916,28,36) not applicable to range of env. (Dominance of NA/european landscapes) temperate communities e.g, water is needed in mediterranean

Question 37

passive rewilding

Answer 37

Broughton et al., 2021 - Rewilding – “restoration of self-regulating and dynamic ecosystems free from direct human interference”

Question 38

rewilding experiment at Mondks Wood national nature reserve

Answer 38

Remote sensing to look at woodland cover To what extent is it evenly distributed or patchy Spatial autocorrelation - establishes the likelihood that a tree is present because there is another growing nearby All tree species showed significant clustering (high spatial autocorrelation) Why? Seed dispersal- wind (anemochory), animal (zoochory) - Eurasian Jay - collects and buries acorns in autumn, find them in winter, hide more than they find, will then germinate and grow

Question 39

cambrian explosion

Answer 39

30Ma pulse in evolutionary activity, expansion in species burgess shale - best record we have of cambrian animal fossils

Question 40

permian mass extinction

Answer 40

96% of all species went extinct (Huang et al 2023) life on earth evolved from the 4%, it is belived that within the 4%, 86% of genetic material was encapsulated. provide opportunities - diversification, reshuffling, reorganisation of ecosystems. can take millions of years for a new equilibrium to become established

Question 41

uniformitariansim

Answer 41

natural processes behave more or less in the same way today as they have throughout the past, and will continue to do so in the future - Hutton 1795

Question 42

loss of megafauna

Answer 42

pleistocene overkill (Martin & Wright, 1967) - longterm steady decline in megaherbivores beginning 4-5 million years ago, long beofre humans were capable of exerting top-down control on large mammals svenning et al (2024) - little support for any major influence of climate …”, and “there is strong and increasing support for human pressures as the key driver of these extinctions”, “but the topic remains controversial”

Question 43

megafaunal extinctions impacts

Answer 43

trophic structure - shorter food chains, simpler ecosystems, abundance and behaviour of grazing animlas ecosytem biochemisty - biogeochemical cycling fo nutrients. nutrients locked slowly into decomposing matter, nutrient poor systems Malhi 2016 - ecosystem physical structure, elephants reduce woody species cover by 15-95% in african savannas

Question 44

allopatric speciation

Answer 44

biological populations become geographically isolated to an extent that prevents or interferes with gene flow. movement of continents, formation of mouuntains, islands - human activity genetic drift, different mutatuons in seperate populations gene pools. Mayr 1942.

Question 45

founder effect

Answer 45

loss of genetic variation when a new population is established by a small number of individuals from a larger population mayr - 1942 new pop may be both geonotypically and phenotypically different from parent population continental islands, continental fragments (madagascar, jamaica), oceanic islands (hawaii)

Question 45

functional diversity

Answer 45

range of functions that organisms can perform in ecosystems enhances ecosystem resillience, supports services, improves resource use efficiency (Gaston, 2006)

Question 46

keller et al 2011

Answer 46

Deccan volcanism and extinction cretaceous-tertiary boundary (66 Ma) rapid warming, acidification, acid rains, carbon ciris 7-8 plankitic foraminiera species survived

Question 47

smit 1989

Answer 47

meteor and KTB Strtigraphy reveals minerals unexplained by volacanism worldwide 8 degree rise in ocean surface temperature

Question 48

ecological release

Answer 48

newly colonising species encounters new environment, competitors are absent loss in unecessary features, defensive traits e.g., Fruit bats in Fiji are more diurnal than those on less isolated islands, as there are no predatory eagles [Ecological release also occurs in ecosystems today, e.g., loss of top predator may change behaviour patterns]

Question 49

loss of dispersal powers

Answer 49

Founding populations clearly had to disperse considerable distances to reach some islands (Hawaii, N america 4000 km away) Once isolates, some birds and insects have developed flightless forms (18/20 endemic species of beetles on Tristan de Cunha have reduced wings) However, flightless species are also found on continents Some island plants also have reduced

Question 50

adaptive radiation

Answer 50

increase in species from an initial ancestor to many descendants, adaptation of these species to different parts of the environment losos et al 2009 Evolutionary development of distinct species (or varieties) from a single ancestral form where radiation occurs due to availability of different ‘empty’ niches. Likely to occur on remote islands lying close to the periphery of a group’s dispersal range – which limits the likelihood of another individual of the same species arriving at the island Hawaiian honeycreepers - Hawaiian birds (25 original colonists resulted in 135 native species, 81% endemic). Originally believed that a single type of ancestral seed-eating finch resulted in radiation to 23 species which filled niches of seed, insect, and nectar feeding species with specialised beaks. Now accepted that there was more than one original species.

Question 51

introduced species

Answer 51

biological invastions are one of top 5 drivers of extinction Gough island (middle of the Atlantic), a British Overseas Territory; one of the most important seabird nesting sites in the world; invasive mice have grown 50% larger than usual as they have no natural predators; they predate eggs and chicks of a range of birds, including critically endangered Tristan albatross (work of the RSPB)

Question 52

easter island

Answer 52

first wave extinction - 900 AD, resource intensive practices (Hunt 2009) tree felling and invasive rats - biggest drivers of extinction exposed forest floor, loss of bird habitats, soil erosion, nutrient leeching 25 sea birds upon arrival, half hunted to extinction, habitat degridation exposed eggs to rats hunt 2006

Question 53

sea otter

Answer 53

keystone species north pacific ocean 1741-1911 extensive hunting - 1000 indivisuals sea urchins primary predator - growth in pop led to overgrazing of kelp forests legeslation restricting hinting, reserves and sanctuaries estes et al 1998

Question 54

Kring 2007

Answer 54

impact causing mass extinction at K-Pg (KTB) boundary crater in mexico, dated precicley to K-Pg energy, shockwaves, wildfires, tsunamis, debris in atm caused impact winter = less sinlight photosynthesis collapsed