Environmental Change - Quaternary and Anthropocene

Question 1

Messinian Salinity Crisis (2.96-5.33Myr) end of the Miocene -> Mediterranean Sea desiccated due to tectonic activity closing the Gibraltar Strait via the Tethys Seaway

Answer 1

evidence in the form of evaporites across the basin -> orbital forcing led to the rapid warming as well

Question 2

Messinian Salinity Crisis -> only extremophiles could cope with the suboxic and anoxic water -> flora and fauna recomposition particularly across the Mediterranean Islands

Answer 2

Betic Seaway formed (landbridge) -> interchange of mammals e.g. camels, mice and elephants (Gilbert et al., 2013)

Question 3

Zanclean Flood (5.33MA) -> Atlantic Ocean reconnected with the Mediterranean Sea via a 200km channel which flooded causing incisional erosion -> Mediterranean filled at 10m/day

Answer 3

biogeography reset as a result

Question 4

Man-made Suze Canal -> connected the Mediterranean Sea and Red Sea = Lesspsian Exchange -> saltier regions act as a filter for biota

Answer 4

core periods of exchange 2010 and 1956 -> canal was widened temporarily during these periods decreasing salinity -> imbalance of migration as Red Sea species better competitors as they are use to harsher environments (Lomolino et al., 2016)

Question 5

The Great American Biotic Interchange (2.8-2.4Myr) -> Isthmus of Panama closed (Bartoli et al., 2005) = interchange of organisms but asymmetrical filter -> mainly N.A to S.A.

Answer 5

N.A. species = better dispersers, speciators, competitors and therefore niches in N.A already saturated AND landbridge formed during dry period -> birdge was grassland which favoured N.A species, evidence = sloths and anteaters from S.A. found in tropical rainforest in S.Mexico but did not move further north (Lomolino et al., 2016)

Question 6

reptiles were the only species that

Answer 6

moved from S.A. to N.A (Lomolino et al., 2016)

Question 7

GABI earlier theories -> landbridge formed via volcanic island formed by Pacific Plate subducted under the Carribbean Plate jioned by volcanic sediment (Cody et al., 2010) -> Gaarlandia was never a complete bridge and was previously a peninsula

Answer 7

evidence -> plant stem nodes identified that some plants migrated from Central to S.A. prior to the closure (Cody et al., 2010) -> ground sloths from S.A. present 9Myr in N.A but the isthmus closed in 3Myr - floated across? (Bacon et al., 2016)

Question 8

Climate during the LGM (20ka) -> ice sheets across NH + Antarctica and mountain glaciers, Beringia refugia, 134m drop in sea levels, increased aridity, tropical rainforest at lower latitudes replaced with savanna (Barry and Chorley, 2009)

Answer 8

species diversity higher during LGM across the 3 European peninsulas -> refugia regions -> lots of species in one region (Petit et al., 2003)

Question 9

Late Pleistocene megafauna extinctions -> globally lost except Africa which only lost 5-18% (Mann et al., 2018) -> modelling revealed that 96% of extinctions were human driven (Smith et al., 2018).

Answer 9

2/3rds of mammals with a body mass > 44kg went extinct (Barnosky and Lindsey, 2010)

Question 10

Stripes and Plaid Hypothesis -> environments constantly shifting due to climatic changes producing plaid environments which species favoured

Answer 10

Holocene halted climatic shifts and environments became striped and more stable -> limited the range of megafauna making them vulnerable to human hunting (Mann et al., 2018)

Question 11

Stripes and Plaid Hypothesis works for Africa -> country retained megafauna as they developed alongside humans

Answer 11

ITCZ, monsoonal precipitation patterns and 23,000yr procession events maintained Africa as a plaid environment (Mann et al., 2018)

Question 12

Broken Zig-Zag Hypothesis

Answer 12

arrival of humans into S.A. disrupted the savanna vs tropical rainforest expansion and contraction relationship and human activity targeted the species populations that tended to be weaker through the environmental conditions (Miotti et al., 2018)

Question 13

Climatic changes as the cause of Late Pleistocene megafauna extinctions (Steward et al., 2021) e.g. Younger Dryas (12.5kyr) – global, rapid cooling is what influenced megafauna but species persisted through other shifts, so the argument is less favourable

Answer 13

human activity exacerbated extinctions through the YD -> 24 genera went extinct during the period in N.A and clovis hunters entered the region at this time (Press-Pulse Theory – extinctions more likely when 2+ ecological impacts are taking place) (Barnosky and Lindsey, 2010).

Question 14

Blitzkreig theory/overkill hypothesis -> arrival of humans times with the extinction of 30 species in N.A and 30 in S.A. -> led to the extinction of the giant ground sloth and mammoths (Anderson et al., 2010)

Answer 14

but Smilodon and Cantonyx remained in S.A 1.5-2.9ka after human arrival (Barnosky and Lindsey, 2011) and assosciational critique -> not enough scavenging/kill sites for all the species lost (Grayson et al., 2021) but this as a criticism was deconstructed by Wolfe and Broughton (2021)

Question 15

Humans transmitting disease as the cause of the Late Pleistocene megafauna extinctions

Answer 15

Fasciola hepatica came from Europe to S.A. in humans and infected deer and camelids leading to their extinction (Pérez and Agnolin, 2021) -> also thought that anthrax and tuberculosis were to blame entering the New World around 10-20ka (Pérez and Agnolin, 2021)

Question 16

Responses to climate change

Answer 16

phenology -> species shift to realign to seasons e.g. flowering in a different period, behaviour = adaptions e.g. amphibians move into water when it is too hot, acclimatisation = phenotypic plasticity as other phenotypes emerge to deal with the environmental conditions (Piglucci et al., 2006) and morphological = structural change to enable the organism a better change at survival (Bellard et al., 2012)

Question 17

Refugia in Eurasia during the LGM -> hedgehog, grasshoppers and Brown Bair -> shifted to the Balkans and S.Italy during glaciations

Answer 17

allopatric speciation of the hedgehog as hybrid zones formed -> led to the western and eastern hedgehog across Europe (Steward and Stringer, 2012)

Question 18

Europe (in 1971) had a phenology network to understand future changes to species, but it shut in 2000 due to a lack of funding

Answer 18

analysed 524 plant species and 19 animal species.

Question 19

Responses to climate change - positive

Answer 19

Yellow-Bellied Marmot -> climate had led to an earlier hibernation and an earlier weaning of the young = longer growing season and the marmot growing.

Question 20

climatic shifts on hominin development -> pulsed climate variability hypothesis (currently accepted theory) -> regular but rapid periods of climate change and longer periods of cooling led to the development of hominins across Africa -> three different proposed routes of the movement of species to Gibraltar, then to the Arabian Peninsula via the Nile valley and to the Arabian Peninsula via the southern Red Sea (Lomolino et al., 2016)

Answer 20

125-70ka -> movement out of Africa, 70-20ka movement into Australasia and Eurasia, 20-10ka -> movement into the America and 10-0ka -> movement around the rest of the globe (Smith et al., 2018).

Question 21

Anthropocene -> sixth mass extinction is taking place as extinction rates far surpass background rates of extinction (Barnosky et al., 2011)

Answer 21

Maslin and Lewis (2015) -> Colombian Exchange with the Orbis Spike -> CO2 decrease detected in the Law Dome Ice Core from E.Antarctica

Question 22

Wilson (2010) HIPPO

Answer 22

Habitat Loss, Invasive Species, Pollution, Human Population, Overharvesting/Overexploitation -> worrying since without biodiversity humanity will likely collapse (Pievani, 2014).

Question 23

Sea LeveL Rise along the Great Barrier Reef

Answer 23

extinction of the Australian Rodent in 2019 (Tuvey and Cress, 2019)

Question 24

bioclimatic modelling/envelope modelling -> using current environmental conditions to determine species distributions and from this project future distributions on projected environmental change

Answer 24

sensitive to the variable and so can often be inaccurate -> land use, projected climate (good GCM), dispersal rates -> often fail to consider metapopulations and disease outbreak (Thomas et al., 2004)

Question 25

improvements in bioclimatic/envelope modelling

Answer 25

can be conducted through consensus modelling -> used as a validation process

Question 26

mechanistic modelling -> overcomes the limitations of bioclimatic modelling - involved mapping species through models e.g. population model or dispersal kernel to produce an environment-demography relationship which can be calibrated to produce a prediction abundance map

Answer 26

statistical modelling -> emphasis on describing the data through mathematical calculations

Question 27

Linnean shortfall (Hortal et al., 2015)

Answer 27

cannot identify all the species within a group as they are fragmented -> limits understandings of species population ranges

Question 28

Signor Lipps Effect

Answer 28

more difficult to determine first datum appearances and last datum appearances as fossil numbers are lower (Stewart et al., 2021)

Question 29

conservation in light of the anthropocene

Answer 29

active species translocation -> taking seeds, spores and pollen outside the natal species range to try and increase population size

Question 30

Krakatau Island 1883 eruption

Answer 30

ideal conditions to analyse recolonisation and succession

Question 31

Future changes -> will species grow more homogenised?

Answer 31

Hawaii -> region has adapted to anthropogenic processes = no native plants rely on native birds for dispersal -> study was conducted over 3 years and 44 plants, and 21 birds were analysed (Vizentin-Bugoni et al., 2019).

Question 32

pollen -> used to identify species patterns e.g. pollen ischrone maps = distributional limits for species or identify refugia regions

Answer 32

e.g. pollen used to identify that Beech entered N. Europe in pulses and was driven by anthropogenic forcing (Lindbladh et al., 2007).

Question 33

models for invasive species -> idealised lognormal frequency distribution to determine changes in species patterns

Answer 33

immigration rates into regions = analysing passive dispersal which follows a sigmoidal curve with a swift drop off and passive dispersal with an exponential curve.

Question 34

Anthropogenic C.C. -> ocean acidification, lake desiccation, coral reef bleaching and sea level rise (Hoegh-Guldberg et al., 2007)

Answer 34

the greatest species loss will take place across New Zealand, S.A. and Australia -> likely as these regions have the highest endemism (Urban, 2015).

Question 35

Research on modelling -> finds that they are overestimating or underestimating (Bellard et al., 2012)

Answer 35

since they fail to account for species dynamics and dispersal mechanisms (Urban, 2015) while species-area relationships tend to incorporate sampling inaccuracies and extinction debt (He and Hubbell, 2011)

Question 36

IUCN -> analysed 9856 birds, 6222 amphibians and 799 coral reef systems

Answer 36

determined that 35% of the bird populations, 52% of the amphibian populations and 71% of coral reefs would be negatively impacted by climate change (Foden et al., 2008)

Question 37

research using models on 9650 systems revealed that climate change would lead to 6,300 species going extinct (Koh et al., 2004)

Answer 37

also a result of plant-pollinator networks crashing (Kiers et al., 2010)