scholarly journals Relative demographic susceptibility does not explain the extinction chronology of Sahul’s megafauna

2020 ◽  
Author(s):  
Corey J. A. Bradshaw ◽  
Christopher N. Johnson ◽  
John Llewelyn ◽  
Vera Weisbecker ◽  
Giovanni Strona ◽  
...  
Keyword(s):  
Climate Change ◽  
Relative Risk ◽  
Prey Choice ◽  
Demographic Rates ◽  
Hunting Success ◽  
Extant Species ◽  
Ecological Mechanisms ◽  
Per Se ◽  
Age Structured ◽  
Taxonomic Groups

AbstractThe causes of Sahul’s megafauna extinctions remain uncertain, although multiple, interacting factors were likely responsible. To test hypotheses regarding plausible ecological mechanisms underlying these extinctions, we constructed the first stochastic, age-structured models for 13 extinct megafauna species from five functional/taxonomic groups, as well as 8 extant species within these groups for comparison. Perturbing specific demographic rates individually, we tested which species were more demographically susceptible to extinction, and then compared these relative sensitivities to the fossil-derived extinction chronology. Here we show that the macropodiformes were the most resilient to extinction, followed by carnivores, monotremes, vombatiform herbivores, and large birds. Five of the eight extant species were as or more susceptible than were the extinct species. There was no clear relationship between extinction susceptibility and the extinction chronology for any perturbation scenario, but body mass and generation length explained much of the variation in relative risk. Our models reveal that the actual mechanisms leading to extinction were unlikely related to variation in demographic susceptibility per se, but were driven instead by finer-scale variation in climate change and/or human prey choice and relative hunting success.

scholarly journals Relative demographic susceptibility does not explain the extinction chronology of Sahul's megafauna

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Corey J A Bradshaw ◽  
Christopher N Johnson ◽  
John Llewelyn ◽  
Vera Weisbecker ◽  
Giovanni Strona ◽  
...  
Keyword(s):  
Climate Change ◽  
Relative Risk ◽  
Prey Choice ◽  
Demographic Rates ◽  
Hunting Success ◽  
Extant Species ◽  
Ecological Mechanisms ◽  
Per Se ◽  
Age Structured ◽  
Taxonomic Groups

The causes of Sahul's megafauna extinctions remain uncertain, although several interacting factors were likely responsible. To examine the relative support for hypotheses regarding plausible ecological mechanisms underlying these extinctions, we constructed the first stochastic, age-structured models for 13 extinct megafauna species from five functional/taxonomic groups, as well as eight extant species within these groups for comparison. Perturbing specific demographic rates individually, we tested which species were more demographically susceptible to extinction, and then compared these relative sensitivities to the fossil-derived extinction chronology. Our models show that the macropodiformes were the least demographically susceptible to extinction, followed by carnivores, monotremes, vombatiform herbivores, and large birds. Five of the eight extant species were as or more susceptible than the extinct species. There was no clear relationship between extinction susceptibility and the extinction chronology for any perturbation scenario, while body mass and generation length explained much of the variation in relative risk. Our results reveal that the actual mechanisms leading to the observed extinction chronology were unlikely related to variation in demographic susceptibility per se, but were possibly driven instead by finer-scale variation in climate change and/or human prey choice and relative hunting success.

scholarly journals Continent-wide tree fecundity driven by indirect climate effects

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
James S. Clark ◽  
Robert Andrus ◽  
Melaine Aubry-Kientz ◽  
Yves Bergeron ◽  
Michal Bogdziewicz ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Distribution Models ◽  
Climate Condition ◽  
Distribution Models ◽  
The West ◽  
Climate Effects ◽  
Continental Scale ◽  
Demographic Rates ◽  
Species Abundances ◽  
Meta Analyses

AbstractIndirect climate effects on tree fecundity that come through variation in size and growth (climate-condition interactions) are not currently part of models used to predict future forests. Trends in species abundances predicted from meta-analyses and species distribution models will be misleading if they depend on the conditions of individuals. Here we find from a synthesis of tree species in North America that climate-condition interactions dominate responses through two pathways, i) effects of growth that depend on climate, and ii) effects of climate that depend on tree size. Because tree fecundity first increases and then declines with size, climate change that stimulates growth promotes a shift of small trees to more fecund sizes, but the opposite can be true for large sizes. Change the depresses growth also affects fecundity. We find a biogeographic divide, with these interactions reducing fecundity in the West and increasing it in the East. Continental-scale responses of these forests are thus driven largely by indirect effects, recommending management for climate change that considers multiple demographic rates.

scholarly journals Global analysis reveals complex demographic responses of mammals to climate change

2019 ◽  
Author(s):  
Maria Paniw ◽  
Tamora James ◽  
C. Ruth Archer ◽  
Gesa Römer ◽  
Sam Levin ◽  
...  
Keyword(s):  
Climate Change ◽  
Climatic Factors ◽  
Global Analysis ◽  
Demographic Data ◽  
Mammal Species ◽  
Full Spectrum ◽  
Terrestrial Mammals ◽  
Demographic Rates ◽  
Global Understanding ◽  
Demographic Responses

ABSTRACTApproximately 25 % of mammals are threatened globally with extinction, a risk that is amplified under climate change1. Persistence under climate change is determined by the combined effects of climatic factors on multiple demographic rates (survival, development, reproduction), and hence, on population dynamics2. Thus, to quantify which species and places on Earth are most vulnerable to climate-driven extinction, a global understanding of how demographic rates respond to climate is needed3. We synthesise information on such responses in terrestrial mammals, where extensive demographic data are available4. Given the importance of assessing the full spectrum of responses, we focus on studies that quantitatively link climate to multiple demographic rates. We identify 106 such studies, corresponding to 86 mammal species. We reveal a strong mismatch between the locations of demographic studies and the regions and taxa currently recognised as most vulnerable to climate change5,6. Moreover, we show that the effects of climate change on mammals will operate via complex demographic mechanisms: a vast majority of mammal populations display projected increases in some demographic rates but declines in others. Assessments of population viability under climate change therefore need to account for multiple demographic responses. We advocate to prioritise coordinated actions to assess mammal demography holistically for effective conservation worldwide.

Eco-evolutionary adaptations of ochotonids (Mammalia: Lagomorpha) to islands: new insights into Late Miocene pikas from the Gargano palaeo-archipelago (Italy)

2020 ◽  
Author(s):  
Blanca Moncunill-Solé
Keyword(s):  
Climate Change ◽  
Growth Rate ◽  
Late Miocene ◽  
Ecological Niche ◽  
Rate Increase ◽  
The Body ◽  
Evolutionary Patterns ◽  
Selective Pressures ◽  
Extant Species ◽  
Management And Conservation

Abstract Climate change strongly affects the range of ochotonids (Order Lagomorpha), fragmenting their habitats and restricting them to ecological islands. The present paper discusses the adaptations of extinct ochotonids to insular stressors, providing baseline data for the management and conservation of extant species. For this purpose, the body mass (BM) and locomotion of the endemic Prolagus apricenicus and Prolagus imperialis from the Gargano palaeo archipelago (Late Miocene) were assessed. P. apricenicus was a small-sized ochotonid (BM 150–250 g) and P. imperialis was probably the largest Prolagus that ever lived (BM 500–750 g). The eco-evolutionary BM dynamics suggest a targeted ecological niche for P. apricenicus, whereas the BM of P. imperialis rose abruptly as a result of growth-rate increase. In both species, the locomotion was stable and less cursorial, with leaping skills, resembling extant rocky ochotonids. Convergent eco-evolutionary patterns are observed in extinct insular ochotonids, concerning an increase of BM (giants), more efficient chewing, less cursorial and more stable locomotion, leaping skills, as well as a slower life history (longer lifespan). Such adaptations are triggered by the specific selective pressures of insular regimes. The present results point to the long-lasting insular Prolagus species as reference taxa for addressing the management of extant rocky ochotonids.

scholarly journals Patterns and ecological determinants of woody plant height in eastern Eurasia and its relation to primary productivity

2019 ◽  
Vol 12 (5) ◽  
pp. 791-803 ◽  
Author(s):  
Zhiheng Wang ◽  
Yaoqi Li ◽  
Xiangyan Su ◽  
Shengli Tao ◽  
Xiao Feng ◽  
...  
Keyword(s):  
Climate Change ◽  
Plant Height ◽  
Primary Productivity ◽  
Water Availability ◽  
Woody Species ◽  
Life Forms ◽  
Geographical Patterns ◽  
Historical Climate ◽  
Geographic Patterns ◽  
Taxonomic Groups

Abstract Aims Plant height is a key functional trait related to aboveground biomass, leaf photosynthesis and plant fitness. However, large-scale geographical patterns in community-average plant height (CAPH) of woody species and drivers of these patterns across different life forms remain hotly debated. Moreover, whether CAPH could be used as a predictor of ecosystem primary productivity is unknown. Methods We compiled mature height and distributions of 11 422 woody species in eastern Eurasia, and estimated geographic patterns in CAPH for different taxonomic groups and life forms. Then we evaluated the effects of environmental (including current climate and historical climate change since the Last Glacial Maximum (LGM)) and evolutionary factors on CAPH. Lastly, we compared the predictive power of CAPH on primary productivity with that of LiDAR-derived canopy-height data from a global survey. Important Findings Geographic patterns of CAPH and their drivers differed among taxonomic groups and life forms. The strongest predictor for CAPH of all woody species combined, angiosperms, all dicots and deciduous dicots was actual evapotranspiration, while temperature was the strongest predictor for CAPH of monocots and tree, shrub and evergreen dicots, and water availability for gymnosperms. Historical climate change since the LGM had only weak effects on CAPH. No phylogenetic signal was detected in family-wise average height, which was also unrelated to the tested environmental factors. Finally, we found a strong correlation between CAPH and ecosystem primary productivity. Primary productivity showed a weaker relationship with CAPH of the tallest species within a grid cell and no relationship with LiDAR-derived canopy height reported in the global survey. Our findings suggest that current climate rather than historical climate change and evolutionary history determine the geographical patterns in CAPH. However, the relative effects of climatic factors representing environmental energy and water availability on spatial variations of CAPH vary among plant life forms. Moreover, our results also suggest that CAPH can be used as a good predictor of ecosystem primary productivity.

Climate Change, Conflicts and Migration

2020 ◽  
pp. 59-82
Author(s):  
Lisa Thalheimer ◽  
Christian Webersik
Keyword(s):  
Climate Change ◽  
Political Economy ◽  
Empirical Evidence ◽  
Environmental Problems ◽  
Per Se ◽  
And Migration ◽  
Governance Arrangements ◽  
Over Time

This chapter focuses on climate conflicts from a political economy perspective. Using the example of droughts in Somalia, the chapter investigates the different drivers of conflict and fragility over time, as well as the relation of changing actors in conflict, environmental disruptions and mixed migration. The chapter shows that there is no empirical evidence to state that climate change per se will increase the number of conflicts and migration. Instead, pre-existing conflicts exacerbate environmental problems that weaken local and national governance arrangements, as well as society’s capacities to deal with climatic shocks, which then can increase migration. However, the authors argue that these relations have to be seen with caution, as conflict-induced and climate-related migration cannot be yet clearly disentangled empirically. Thus, the authors conclude the need for streamlined, flexible governance measures to address climate conflicts.

scholarly journals Individual-scale inference to anticipate climate-change vulnerability of biodiversity

2012 ◽  
Vol 367 (1586) ◽  
pp. 236-246 ◽  
Author(s):  
James S. Clark ◽  
David M. Bell ◽  
Matthew Kwit ◽  
Anne Stine ◽  
Ben Vierra ◽  
...  
Keyword(s):  
Climate Change ◽  
Individual Tree ◽  
Demographic Rates ◽  
Competitive Environments ◽  
Scale Models ◽  
Competition For Light ◽  
Input Variables ◽  
Individual Scale ◽  
The Individual ◽  
Demographic Responses

Anticipating how biodiversity will respond to climate change is challenged by the fact that climate variables affect individuals in competition with others, but interest lies at the scale of species and landscapes. By omitting the individual scale, models cannot accommodate the processes that determine future biodiversity. We demonstrate how individual-scale inference can be applied to the problem of anticipating vulnerability of species to climate. The approach places climate vulnerability in the context of competition for light and soil moisture. Sensitivities to climate and competition interactions aggregated from the individual tree scale provide estimates of which species are vulnerable to which variables in different habitats. Vulnerability is explored in terms of specific demographic responses (growth, fecundity and survival) and in terms of the synthetic response (the combination of demographic rates), termed climate tracking. These indices quantify risks for individuals in the context of their competitive environments. However, by aggregating in specific ways (over individuals, years, and other input variables), we provide ways to summarize and rank species in terms of their risks from climate change.

scholarly journals TECHNOLOGICAL AGNOSTICISM AND CLIMATE CHANGE: PLATFORM CULTURE ON TECHNOLOGY FORUM WHIRLPOOL

2021 ◽  
Author(s):  
Aleesha Joy Rodriguez
Keyword(s):  
Climate Change ◽  
Thematic Analysis ◽  
Future Research ◽  
Energy Technologies ◽  
Climate Change Denial ◽  
Per Se

This paper explores the (limited) discussion of climate change within energy debates on Australian technology forum Whirlpool. These discussions are characterised by $2 , which is an attitude that no technology is $2 or $2 than any other because different technologies have different applications depending on the requirement. By completing a thematic analysis of all Whirlpool replies within four threads centred on energy debates (n = 3,101), I observed Whirlpool contributors depoliticise energy technologies by removing climate change as a factor when considering technology choices. Overall, I found that when technological agnosticism was expressed within these debates, it intersected with issues concerning the $2 , $2 , $2 , and $2 of technology and pushed against concerns regarding climate change. I argue that the prevalence of technological agnosticism within these debates is not an example of climate change denial per se but a reflection of Whirlpool’s platform culture which valorises traits of $2 such as rationality and neutrality (Massanari, 2017). I conclude by comparing Whirlpool’s platform culture to Reddit and suggest that future research ought to explore how particular platform cultures shape energy debates and ultimately, attitudes and action towards climate change.

scholarly journals Seasonal and successional dynamics of size-dependent plant demographic rates in a tropical dry forest

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9636
Author(s):  
Irving Saenz-Pedroza ◽  
Richard Feldman ◽  
Casandra Reyes-García ◽  
Jorge A. Meave ◽  
Luz Maria Calvo-Irabien ◽  
...  
Keyword(s):  
Climate Change ◽  
Tropical Forests ◽  
Dry Season ◽  
Dry Forest ◽  
Species Density ◽  
Wet Season ◽  
Successional Stage ◽  
Size Dependent ◽  
Demographic Rates ◽  
Successional Stages

Tropical forests are globally important for biodiversity conservation and climate change mitigation but are being converted to other land uses. Conversion of seasonally dry tropical forests (SDTF) is particularly high while their protection is low. Secondary succession allows forests to recover their structure, diversity and composition after conversion and subsequent abandonment and is influenced by demographic rates of the constituent species. However, how these rates vary between seasons for different plant sizes at different successional stages in SDTF is not known. The effect of seasonal drought may be more severe early in succession, when temperature and radiation are high, while competition and density-dependent processes may be more important at later stages, when vegetation is tall and dense. Besides, the effects of seasonality and successional stage may vary with plant size. Large plants can better compete with small plants for limiting resources and may also have a greater capacity to withstand stress. We asked how size-dependent density, species density, recruitment and mortality varied between seasons and successional stages in a SDTF. We monitored a chronosequence in Yucatan, Mexico, over six years in three 0.1 ha plots in each of three successional stages: early (3–5 years-old), intermediate (18–20 years-old) and advanced (>50 years-old). Recruitment, mortality and species gain and loss rates were calculated from wet and dry season censuses separately for large (diameter > 5 cm) and small (1–5 cm in diameter) plants. We used linear mixed-effects models to assess the effects of successional stage, seasonality and their changes through time on demographic rates and on plant and species density. Seasonality affected demographic rates and density of large plants, which exhibited high wet-season recruitment and species gain rates at the early stage and high wet-season mortality at the intermediate stage, resulting in an increase in plant and species density early in succession followed by a subsequent stabilization. Small plant density decreased steadily after only 5 years of land abandonment, whereas species density increased with successional stage. A decline in species dominance may be responsible for these contrasting patterns. Seasonality, successional stage and their changes through time had a stronger influence on large plants, likely because of large among-plot variation of small plants. Notwithstanding the short duration of our study, our results suggest that climate-change driven decreases in rainy season precipitation may have an influence on successional dynamics in our study forest as strong as, or even stronger than, prolonged or severe droughts during the dry season.

scholarly journals GENDER AND CLIMATE CHANGE

2021 ◽  
Author(s):  
Prachi Ugle Pimpalkhute
Keyword(s):  
Climate Change ◽  
Decision Making ◽  
Indigenous Knowledge ◽  
Gender Bias ◽  
Gender Disparities ◽  
Local Action ◽  
Knowledge Repository ◽  
Climate Action ◽  
Common Framework ◽  
Per Se

The impacts of climate action is not bound by gender disparities, but still each one ofus is accountable and responsible for its management. Climate action has to be scientific expression of attributes working in synchronously with multi-stakeholders and a common framework or exchange of dialogues. If equity in action is a perspective per se, then equality in gender towards steering it forward is a gender attribute. Women, men, children and other stakeholders are all impacted, and beyond gender bias one has to work on then targets. Women face inequalities and have not been given the key role in decision making, local and indigenous knowledge repository is used for local action by women and their contribution fixes many local issues.

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