Topic 3: Biodiversity and conservation

Question 1

biodiversity

Answer 1

biodiversity is a broad concept encompassing the total diversity of living systems / biodiversity includes the species, habitat and genetic diversity within an area / the amount of biological diversity per unit are

Question 2

endemic species

Question 3

Define species diversity.

Answer 3

species diversity is the function of the number of species/richness and their relative proportions/abundance/evenness (in an area);

Question 4

Explain why the diversity changes in the different successional stages.

Answer 4

Species diversity increases toward the later stage…

because there is an increase in habitats;
as new species move or are transported into the area;
because primary productivity tends to increase as you move through the stages;
because nutrient cycling becomes more developed;
because evenness/richness increases;

Question 5

Outline the factors that contribute to total biodiversity of an ecosystem.

Answer 5

biodiversity includes the diversity of species, habitat and genes;
species diversity involves both the variety/number of species/richness and their relative proportions/evenness;
habitat diversity refers to the range of different habitats in an ecosystem or biome;
…which may vary due to environmental gradients/changing abiotic conditions/altitude/latitude/major disturbances (volcanic activity/landslides, etc);
habitat/niche diversification promotes species diversity;
genetic diversity refers to the range of genetic material/genes in a population/species;
…which is influenced by mutation/sexual reproduction/natural selection/speciation;
high primary productivity/insolation/precipitation/optimum abiotic conditions promote biodiversity;
succession promotes greater biodiversity by increasing length/branching of food chains / because it leads to improved abiotic conditions.

Question 6

discuss whether biodiversity loss or climate change is a greater threat to human societies.

Answer 6

understanding concepts and terminology biodiversity (habitat, species, genetic); climate change; threats to ecosystems from biodiversity loss; threats to ecosystems from climate change; impact of these on human societies; threats to food production from both; extinction; hotspots; sustainable development goals;
breadth in addressing and linking tipping points; positive and negative feedback loops; regime shifts/alternative stable states; possible use of solutions to address challenges of each threat (mitigation, adaptation, conservation strategies); benefits of biodiversity; ecosystem resilience; ecosystem stability; biome shift; loss of keystone species; conservation, EVSs; uncertainty of GCC impacts/modelling;
examples of scale of biodiversity loss; impacts to food webs/productivity/ecosystems; examples of climate change impacts on ecosystems/society/economics/energy production (at both global and local scale); examples of causes of biodiversity loss and of climate change;
balanced analysis two-way (bidirectional) interaction of climate change and biodiversity loss; contrast efficiency/difficulty of conservation/management strategies to mitigation/adaptation strategies (in the context of different EVSs); political implications (national & international agreements, role of NGOs); compare present rate and scale to past events; contrast local to global scale;
a conclusion that is consistent with, and supported by, analysis and examples given e.g. I believe climate change is a bigger threat to human societies as it will result in biodiversity loss in more systems than areas which could gain in biodiversity and result in multiple impacts on human health, human populations from severe weather, however without building ecosystem resilience through preserving biodiversity, climate change will be even more of a threat to human societies;
c.

Question 7

Identify four reasons why the genetic diversity of a population may change over time.

Answer 7

mutation may lead to new genotypes/increased diversity;

natural selection/survival of fittest may eliminate some genotypes/reduce diversity;

(human activities) eg pollution/hunting/habitat destruction/alien species may reduce population/diversity / lead to a bottleneck effect;

migration causing mixing of populations/subjection to new selective pressures;

climate change may eliminate certain genotypes/reduce diversity;

…or lead to evolution of new genotypes/increase diversity;

(tectonic activity may create) natural barriers leading to divergent evolution/speciation/greater diversity;

genetic drift/random loss of genes;

Question 8

State two possible causes of these past mass extinctions.

[2]a.

Answer 8

meteorite/asteroid/comet impacts;
significant volcanic events/volcanic eruptions/basalt flows;
climate change/ice age;
catastrophic methane release (e.g. from methane clathrate);
drop in oxygen levels;
sea level changes;
cosmic events/radiation from space that depletes atmospheric ozone.

Question 9

Outline how the process of natural selection is a mechanism for evolution.

[2]d.

Answer 9

organisms in any population vary;

some traits make them better adapted to survive / selection pressures in the environment may favour some variations over others/‘the survival of the fittest’;

thus organisms become adapted to environmental conditions;

some of these variations give it a competitive advantage leading to breeding success / those organisms that survive are able to breed and pass on their traits to their offspring;

where conditions (e.g. climate) change, the organism may respond by adapting to it;

isolation (geographical/ecological/reproductive) may separate a part of a population from others;

differences in the environments may cause speciation/evolution of new species as the population adapts to the new environment;

the new species may be unable to interbreed with the parent species to produce fertile offspring.

[2 max]

d.

Question 10

Identify the relationship between the number of continents and the diversity of species during the past 250 million years.

Answer 10

the greater the number of continents, the greater the diversity / positive correlation

Question 11

Outline the role of natural selection in increasing the diversity of species.

Answer 11

natural selection (resulting from changing environment) acts on existing genetic variation (that has arisen through mutations over the eons);
natural selection increases the survival of fittest genetic variations/traits;
these traits are heritable/passed onto offspring / selected individuals will have higher reproduction potential / so species will adapt to different environments;
the proportion of these traits may increase in some populations/in subsequent generations;
which can lead to speciation/increasing species diversity if there is reproductive isolation;

Question 12

suggest how fish diversity may be influenced by the habitat diversity of the Coral Triangle.

Answer 12

high diversity of habitats/variety of habitats provide a variety of niches that supports high fish diversity / high diversity of habitats/seagrass/corals/mangroves leads to high diversity of fish;
variety of habitats provide different food sources that support a wide range of fish species;
variety of habitats provide different breeding/nursery grounds for diversity of fish;
variety of habitats provide different shelter/protection from predators which increases fish diversity;

Question 13

identify two factors that may have contributed to their status given on the IUCN Red List.

Answer 13

reduction in population size;
population size / numbers of mature individuals / number of individuals able to reproduce;
geographical range / area of occupancy (ie where species are normally found) / extent of occurrence (boundary line that can be drawn around sites that the species occupies);
reduction in number of locations (the species is found in);
degree of fragmentation (eg via road or urban development);
quality of habitat / loss of habitat / habitat degradation;
probability/high risk of extinction.

Question 14

Explain how changes in the concentration of stratospheric and tropospheric ozone in the atmosphere can affect global biodiversity.

Answer 14

change in stratospheric ozone allows more UV radiation to reach earth;
…which causes mutations/damage to DNA/cancers;
…(possibly) resulting in death of organisms/reduction in biodiversity;
…also reduces plant growth/NPP/especially phytoplankton / damages chlorophyll;
…affecting populations all along food chain/reducing diversity of food web; [4 max]

change in tropospheric ozone in urban areas gives rise to photochemical smog;
…that is toxic (to humans/other species);
…damages plant leaves reducing NPP of ecosystems/food chains;
…tropospheric ozone is a greenhouse gas contributing to global warming/climate change;
…resulting in population declines/death/reduction in biodiversity; [4 max]

Question 15

Identify two reasons why the future size of the Atlantic puffin population is difficult to predict.

Answer 15

multiple interrelated threats affecting them;
impact of extreme weather/impact of climate change not fully understood;
unexpected diseases may affect population numbers;
inaccuracies in population counts;
large geographical range makes representative sampling difficult;
difficult to predict future number of prey species/food availability/difficult to predict number of competitors (eg mackerel);
calculations only based on estimates with large margin of error;
in future changes may be made to the management/legislation/policies on puffins (eg hunting of puffins may be banned);

NB Do not credit for only over-hunted/overfishing/is part of a complex food web/‘weather’.

Question 16

Explain one factor that may make a species less prone to extinction.

Answer 16

reach sexual maturity early;
…which means they are able to produce offspring early/have more offspring/have larger populations (and increase their species chances of success);

they can have high reproductive success/produce large number of offspring;
…large populations can increase the chances of their survival;

they are opportunistic /r species able to adapt to a wide variety of conditions;
…this allows them to be present in many habitats / have wide geographical coverage;

they have fast lifecycles (e.g. r species);
…which allows them to adapt quickly to change;

they have a number of habitats they can shelter/live/ are widely distributed;
…so if a population is affected in one habitat (e.g. by disease/predation) the species will still survive in another habitat/location;

they are omnivores/generalist feeders/switching predators;
…this adaptability to eating different foods results in potentially a large available food source/with some food source available even under harsh conditions;

ability to hide/camouflage/successfully fight;
…which can reduce predation rates and increase chances of species survival;

have high genetic diversity;
…they are able to adapt to changing environmental conditions;

valued by humans (e.g. as keystone/flagship species);
..increases human investment/action into conserving the species/its habitat (e.g. Giant Panda);

not considered valuable by humans (e.g. as pets or making ornaments);
…it is not hunted /removed from habitat thereby reducing risk of extinction.

Question 17

Discuss how the introduction and re-introduction of a species can affect an ecosystem.

[9]c.

Answer 17

models of ecosystems can give holistic perspective on conservation;
flows of energy and matter / box-and-arrow models can be used to identify key storages/processes for conservation;
modelling may consider biodiversity measures to help in evaluating conservation;
measures of genetic diversity help to determine breeding plans for species conservation;
physical models can help in studying abiotic needs of a species;
modelling feeding interactions / predator-prey interactions allows conservationists to determine the needs of species;
modelling feeding interactions can demonstrate possible trophic cascades and provide information about benefits of conservation;
modelling biotic interactions can help identify potential threats/essential interactions to the conservation of a species;
modelling energy/matter flows helps determine habitat needs/area for a species;
modelling is likely to be used in combination with field observations/community needs;
modelling may miss emergent properties of a system and therefore not help in species conservation;
modelling may not take account of human activities / unpredictable events;
modelling may not take account of rare events, such as natural disasters;
mathematical modelling may quantify population dynamics;
….thus allow predictions on probability of extinction/recovery;
microcosm may study effects of disturbance on species;
single species models may be too simplistic and fail to predict actual behaviour of ecosystem
zoos can be designed to reflect the specific features of an endangered species niche;
b.

Question 18

Explain the causes, and the possible consequences, of the loss of a named critically endangered species.

Answer 18

Causes [4 max] could include:
habitat loss / deforestation;
habitat degradation / pollution;
narrowly distributed / endemic;
poaching / overhunting;
illegal trafficking of species;
disease;
small population size/gene pool / inbreeding;
specialised niche;
slow reproduction rate / specialised reproductive behaviour;
high trophic level/top predator;
low/negative cultural value;
influence/competition/predation from invasive species.

Consequences [4 max] could include:
loss of an aesthetically attractive organism;
loss of ethically significant life / breach of biorights;
loss of biodiversity;
increase in organisms upon which the species fed or competed with;
decline in other organisms due to loss of food source;
if keystone species, widespread impacts/cascade effects on food chains/ecosystem;
economic costs from loss of ecosystem services provided by the species;
economic costs from loss of tourism opportunities;
social impacts on local culture as important/significant cultural loss.

Question 19

Outline one advantage of increased tourism on wildlife conservation.

[1]a.
Outline one disadvantage of increased tourism on wildlife conservation.

[1]b.

Answer 19

increased revenues to invest back into conservation;
raises awareness leading to greater support/public engagement with wildlife conservation;
consideration of wildlife as an asset that needs to be looked after;
if local population have jobs in the tourism industry they are less likely to engage in unsustainable tavy farming/fishing activities.

HOWEVER
growth in tourist sites/hotels could cause loss of habitats/forests;
creation of roads that fragment habitats;
noise from tourism that disrupt wildlife/mating / disturbances caused by tourists can alter animal behaviour;
litter that can degrade environment / harm wildlife;
increased tourism puts greater demand on limited freshwater that is unsustainable / increase demand for limited water resources that competes with wildlife;
greater access to wildlife areas that could lead to increased poaching/illegal fishing/increase capture for illegal pet trade;
increase in tourism could increase demand of goods/services that cause deforestation/use unsustainable resources (e.g. fossil fuels);
animals/wildlife used as a tourist attraction maybe inappropriately/unethically treated / focus on popular tourist sites may leave less visited sites with fewer conservation resources/funds.

Question 20

Distinguish between the concept of a “charismatic” (flagship) species and a keystone species using named examples.

Answer 20

charismatic/flagship eg Panda/Tiger and keystone eg Northern Spotted Owl/Sea Stars/Fig Trees/Sea Otters/Jaguar;

Award 3 max for valid points of distinction:
charismatic/flagship species are used to publicise/advertise conservation campaigns/stimulate public action/raise economic support;
…they are selected because they appeal to humans/have ideological/cultural/religious significance;
their value is primarily subjective/relative to a society rather than ecological;
keystone species have a disproportionately large effect on their environment/may determine structure of an ecosystem/have many other species dependent on them;
keystone species may be publicly unpopular/threat to locals/considered pests/killed for fur/trophy;
they are identified through ecological/scientific/objective study of their relationships with the entire ecosystem;

Question 21

Discuss the implications of environmental value systems in the protection of tropical biomes.

Answer 21

understanding concepts and terminology of environmental value systems, tropical biomes, biodiversity, conservation, habitat v species approach, reserves, ecotourism, flagship species, sustainable development/exploitation, goods/services.
breadth in addressing and linking environmental value systems with each other and ecocentric values with biorights, wilderness reserves, restrained resource use, etc and anthropocentric values with laws/regulations/quotas, public consultation/agreements, sustainable exploitation, ecotourism etc and technocentric values with economic development, habitat restoration, economic value of natural goods and services, gene banks etc
examples of tropical biomes e.g. tropical forests, grasslands, savannas, lakes & rivers, coral reefs etc and environmental value systems eg ecocentrism, anthropocentrism, technocentrism, etc and habitat/species protection strategies eg reserves, managed sustainable harvesting, ecotourism, fishing quotas, etc and value systems in specific tropical societies eg rights of nature enshrined in constitutions of Ecuador/Bolivia, human rights to a healthy environment in laws of Costa Rica/Brazil, etc
balanced analysis of the ways in which different value systems are likely to impact/influence the protection of tropical biomes, acknowledging relevant counter-arguments/alternative viewpoints.
a conclusion that is consistent with, and supported by, analysis andexamples given eg “Because ecocentric values embrace the biorights of all living species and habitats their implications are bound to be the most fundamentally protective, however, to be practical in current society, more is likely to be achieved in protecting tropical biomes through some compromise with other value systems.” NB This is only an example of a possible conclusion. Candidates’ conclusions do not have to agree

Question 22

To what extent is the need for conservation more significant in tropical biomes?

Answer 22

understanding concepts and terminology of biodiversity; conservation strategies; tropical biomes; rainforests; swamps; coral reefs; hotspots; LEDCs & MEDCs; international v national conservation bodies; environmental value systems; productivity; carbon sinks; global warming; unsustainable exploitation; resources of tropical ecosystems; medicines; indigenous cultures; endangered species; Red List, etc.;
breadth in addressing and linking threats to biodiversity with different societies, ecosystems, conservation strategies; the global dependence upon and significance of tropical biomes compared with others; implications of economic development in tropical regions with challenges of conservation; different EVS perspectives on reasons for conservation, etc.;
examples of tropical biomes/ecosystems; their local societies; conservation efforts; reasons/needs for conservation, etc.;
balanced analysis evaluating the extent to which conservation efforts are of particular importance for tropical biomes along with relevant limitations and counterarguments, etc.;
a conclusion that is consistent with, and supported by, analysis and examples given e.g. “although the loss of any species may be considered of equal significance from an ecocentric point of view, the high productivity and biodiversity that characterize tropical biomes, along with the limited facility of local societies, which are often less developed, make tropical biomes a priority for international conservation efforts”;
c.

Question 23

Identify two difficulties associated with establishing and maintaining wildlife corridors such as those shown in Figure 6(d).

Answer 23

cost of acquiring/managing large areas;
the large areas covered by wildlife corridors can make it difficult to manage;
policing against poaching / greater vulnerability to poaching / corridors are narrow and more affected by edge effect / corridors may pass near or over roads resulting in some roadkill;
displacement of human settlement/industry / may create conflict with people’s use of land e.g. for agriculture;
difficult to determine where to site wildlife corridors / land which is suitable must be available;
challenges of international collaboration;
spread of disease/invasive species from one region to another;

Question 24

Using examples, discuss whether habitat conservation is more successful than a species-based approach to protecting threatened species.

Answer 24

understanding concepts & terminology of habitat-based methods for conservation; species-based methods for conservation; international and national protection; international, national and local conservation organisations; ecosystem services; food chains and food webs; succession; threats to biodiversity; pollution consequences, eg bioaccumulation and biomagnification; threats from climate change; food production systems; human population growth; sustainable development; EVSs;
breadth in addressing and linking range of threats to biodiversity; scale of different threats; challenges in LEDCs to develop sustainably; consequences of different EVSs; variety of habitat-based methods for conservation; variety of species-based methods of conservation;
examples of both habitat- and species-based methods; threatened and protected areas and species; organisations involved in conservation;
balanced analysis of the varying success of habitat and species conservation to protect threatened species;
a conclusion that is consistent with, and supported by analysis and examples given eg success of the conservation of threatened species will depend on the context, nature of the threats and a combination of strategies is likely to be necessary with both habitat and species approaches used. If the habitat is not conserved and restored, a species whose population has been increased using species-based methods, will not survive in the wild.

Question 25

discuss the significance of diversity in the sustainability of food production systems.

Answer 25

understanding concepts and terminology of genetic/species/habitat diversity; cultural / political diversity; sustainability; ecological footprint; yield per unit area; aquatic and terrestrial food production; commercial vs. subsistence; multinational vs. local production; monoculture v polyculture; organic farming; GMOs; selective breeding; impact of escapees on wild populations; integrated agriculture; habitat loss/degradation; air/water/soil pollution; threats to biodiversity/pollinators; pesticide/fertilizer/antibiotic use; biological pest control; food choice; buffer zones; mineral cycles; crop rotation, etc.;
breadth in addressing and linking technological and management strategies of terrestrial and aquatic food production systems with genetic/species/habitat diversity and significance of this in terms of sustainability and ecological footprint in the context of a range of geographical locations, social settings, levels of economic development, traditional values, international relations, legislations, personal attitudes and EVSs, etc.;
examples of named food production systems and strategies involved in monoculture, polyculture and integrated agriculture, wild fisheries, aquaculture etc.;
balanced analysis evaluating the extent to which diversity is significant in determining the sustainability of food production systems along with relevant limitations and counterarguments, etc.;
a conclusion that is consistent with, and supported by, analysis and examples given e.g. “because diversity is such a significant factor in maintaining stability of systems, it is inevitably of great significance in maintaining both a sustainable production system and the wider environment in which the production takes place”;