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Reef-building corals are found across > 30° of latitude from tropical to temperate regions, where they occupy habitats greatly differing in seawater temperature and light regimes. It remains largely unknown, however, how the demography of corals differs across this gradient of environmental conditions. Variation in coral growth is especially important to coral populations, because aspects of coral demography are dependent on colony size, with both fecundity and survivorship increasing with larger colonies. Here we tested for latitudinal variation in annual growth rate and survival of juvenile corals, using 11 study locations extending from 17° S to 33° N in the West and South Pacific. Regression analyses revealed a significant decline in annual growth rates with increasing latitude, whereas no significant latitudinal pattern was detected in annual survival. Seawater temperature showed a significant and positive association with annual growth rates. Growth rates varied among the four common genera, allowing them to be ranked Acropora > Pocillopora > Porites > Dipsastraea. Acropora and Pocillopora showed more variation in growth rates across latitudes than Porites and Dipsastraea. Although the present data have limitations with regard to difference in depths, survey periods, and replication among locations, they provide evidence that a higher capacity for growth of individual colonies may facilitate population growth, and hence population recovery following disturbances, at lower latitudes. These trends are likely to be best developed in Acropora and Pocillopora, which have high rates of colony growth.

Arctic Terns (Sterna paradisaea) share a few routes to undertake the longest annual migrations of any organism. To understand how the wide spatial range of their breeding colonies may affect their migration strategies (e.g., departure date), we tracked 53 terns from five North American colonies distributed across 30° of latitude and 90° of longitude. While birds from all colonies arrived in Antarctic waters at a similar time, terns nesting in the Arctic colonies migrated back north more slowly and arrived to their breeding grounds later than those nesting in the colony farther south. Arrival dates in Antarctic waters coincided with the start of favorable foraging conditions (i.e., increased ocean productivity), and similarly arrival dates at breeding colonies coincided with the start of local favorable breeding conditions (i.e., disappearance of snow and ice). Larger birds followed a more direct southbound migration route than smaller birds. On both southbound and northbound migrations, daily distances traveled declined as time spent in contact with the ocean increased, suggesting a trade-off between resting/foraging and traveling. There was more unexplained variation in behavior among individuals than among colonies, and one individual had a distinctive stop around Brazil. Terns nesting in the Arctic have a narrow time window for breeding that will likely increase with continuing declines in sea ice and snow. Departing Arctic Terns likely have few clues about the environmental conditions they will encounter on arrival, and their response to environmental changes at both poles may be assisted by large individual variation in migration strategy.

Seeds are crucial for plant population maintenance and dispersal. Invasive species often exhibit seed traits that enhance their colonization success, such as increased dispersal potential, earlier germination, or greater resource reserves. However, few studies have compared seed traits between invasive and native plant species along environmental gradients. Here, we compared morphological traits and nutrient concentrations of the seeds of two competing species, the native common reed ( Phragmites australis ) and the invasive saltmarsh cordgrass ( Spartina alterniflora ), along a 20° latitudinal gradient of the Chinese coast, and their relationships with environmental factors. Significant differences were found between the two species for 11 of the 13 traits with respect to latitude. Specifically, the seed size of S. alterniflora decreased with increasing latitude, but P. australis showed a slight curvilinear relationship with latitude, reducing to a minimum between 30 and 35° N. The latitudinal variation in seed set showed the opposite trends in both species at high latitudes. Seed nitrogen concentration decreased with latitude in both species, while seed phosphorus concentration declined only in P. australis . We also identified that temperature-dependent climatic variables were more important than soil properties in affecting the latitudinal variations of seed traits for both species, especially for S. alterniflora . Based on the results, we predict that the greater fecundity of S. alterniflora populations poses an increasing threat to P. australis at the higher latitudes as temperature rises due to climate change.

We performed stable carbon (δ13C) and nitrogen (δ15N) isotope analyses of 12 ancient Adélie penguin (Pygoscelis adeliae) chick mummies recovered from abandoned colonies in the Ross Sea region, Antarctica, to investigate isotopic variation and fractionation over time. We also examined latitudinal variation in penguin diet to address if the modern dietary pattern (an increase in krill as dominant prey to the north) in this region has existed in the past or if this is a recent phenomenon. The ancient mummies range in age from > 48,000 14C years before present (BP) to ~ 500 calendar years BP. Feather, skin, bone, and toenail samples were analyzed from each individual where available. Identical analyses were performed on five modern mummified Adélie penguin chick carcasses and breast feathers of ten recently dead chicks from each of two active colonies, Cape Hallett and Adélie Cove. We found significantly lower δ15N values in Cape Hallett modern chicks as compared to those from Adélie Cove, indicating an entire trophic-level difference in modern diet that agrees with other studies in this region. The ancient mummies exhibited consistent isotopic fractionation of δ13C among the four different tissues through time. Variation in δ15N and δ13C values was greater in bone and skin than in feather or toenail, but δ15N in all four tissues indicated similar dietary trends with latitude as occurs in this region today. These results provide insight into the dietary variability of Adélie penguins across the Ross Sea region and a framework for similar analyses with other avian species.

Tropical coastal areas are amongst the most diverse ecosystems in the world. However, there are quite a few coasts that have rarely been studied for their macro-benthic diversity. The Indian coastline presents one such gap area. Two sub-parallel coastlines of India have a wide latitudinal span (8–23°N) and strikingly different physiographic environments. While the east coast receives a high siliciclastic input from large river systems flowing to the Bay of Bengal with fluctuating salinity, the west coast has a large shelf area and high productivity of the Arabian Sea. Such difference enables us to evaluate the effect of regional environmental parameters on marine molluscan diversity and distribution in an intra-tropical setting. Because of the wide latitudinal range, it is also possible to assess if spatial difference in species richness in such a regional scale follows the large-scale biodiversity pattern such as Latitudinal Biodiversity Gradient (LBG) despite inherent environmental variation. We used species distribution of marine bivalves, compiled using bioSearch and the Ocean Productivity database, to address this question. Our results show that intra-tropical species richness of marine bivalves is guided primarily by regional environmental parameters. Even with identical latitudinal extent, higher nutrient availability and larger shelf area, the west coast has significantly lower richness than the east coast; among environmental variables, productivity, salinity and coastline length emerged as significant predictors of species diversity. Moreover, a positive influence of a South Asian biodiversity hotspot on east coast fauna and a negative impact of the oxygen-depleted condition of Arabian Sea on west coast fauna, may have a significant contribution in developing such coastal variation in species richness. The latitudinal variation in species richness did not follow LBG. In contrast to the coast-specific diversity difference, species composition is not found to be dictated by coastal affiliation. The composition corresponds primarily to physiographic conditions. We identified three distinct eco-regions (north-western, southern, north-eastern) with characteristic species composition corresponding to unique physiography and productivity mechanism. The NW region has low siliciclastic input and high productivity associated with upwelling during winter cooling. The NE region has a distinctly high riverine input and salinity fluctuation. The southern region, in contrast, has well developed reefal system with moderate variation in salinity. Such correspondence underscores the importance of the regional environment in dictating the species diversity and distribution in the shallow marine realm.

• Feral plants have evolved from well-studied crops, providing good systems for elucidation of how weediness evolves. As yet, they have been largely neglected for this purpose. The evolution of weediness can occur by simple back mutations in domestication genes (domestication in reverse). Whether the evolutionary steps to weediness always occur in reverse remains largely unknown. • We examined seed germination behavior in recently evolved weedy rice (Oryza sativa f. spontanea) populations and their coexisting cultivars in eastern and north-eastern China to address whether ‘dedomestication' is the simple reverse of domestication. • We found that these weedy populations did not diverge from their progenitors by reverting to the pre-domestication trait of seed dormancy. Instead, they have evolved a novel mechanism to avoid growing in inappropriate environments via changes in critical temperature cues for seed germination. Furthermore, we found evidence for subsequent ecotypic divergence of these populations such that the critical temperature for germination correlates with the local habitat temperature at latitudinal gradients. • The origins of problematic plant species, weeds and invasives, have already been studied in detail. These plants can thus be used as systems for studying rapid evolution. To determine whether and how that evolution is adaptive, experiments such as those described here can be performed.

A long-term mean turbulent mixing in the depth range of 200–1000 m produced by breaking of internal waves across the middle and low latitudes (40°S–40°N) of the Pacific between 160°W and 140°W is examined by applying fine-scale parameterization depending on strain variance to 8-year (2005–2012) Argo float data. Results show that elevated turbulent dissipation rate ( ε ) is related to significant topographic regions, along the equator, and on the northern side of 20°N spanning to 24°N throughout the depth range. Two patterns of latitudinal variations of ε and the corresponding diffusivity ( K ρ ) for different depth ranges are confirmed: One is for 200–450 m with significant larger ε and K ρ , and the maximum values are obtained between 4°N and 6°N, where eddy kinetic energy also reaches its maximum; The other is for 350–1000 m with smaller ε and K ρ , and the maximum values are obtained near the equator, and between 18°S and 12°S in the southern hemisphere, 20°N and 22°N in the northern hemisphere. Most elevated turbulent dissipation in the depth range of 350–1000 m relates to rough bottom roughness (correlation coefficient = 0.63), excluding the equatorial area. In the temporal mean field, energy flux from surface wind stress to inertial motions is not significant enough to account for the relatively intensified turbulent mixing in the upper layer.

Air temperature data at weather stations in the Northern Hemisphere and astronomical insolation data were ordered by increasing latitude and analyzed together for different samples between 1897 and 2010. Using a step-by-step regression of the latitudinal variation in the long-term average temperature to a polynomial of astronomical insolation, a latitudinal trend in the temperature determined by the Sun and fluctuating regression residuals, which characterize individual features of data, are identified. The absence of interaction of these components is numerically achieved for any samples. It has been found that the latitudinal trend in the long-term average temperature completely determines the warming and contributes about 82% to the total temperature dispersion in the Northern Hemisphere for available samples. The boundaries of regions where temperatures are above and below the latitudinal trend in the long-term average temperatures reveal known geographic structures, thus verifying the trend.

Heat tolerance at the immobile embryonic stage is expected to be critical in determining species vulnerability to climate change. However, how the mean and developmental plasticity of embryonic heat tolerance vary geographically, and how these geographic variations affect species' vulnerability under climate change remain unknown. We experimentally determined the mean and developmental plasticity of embryonic acute heat tolerance (EAHT, i.e., heat shock temperature at which embryonic heartbeats ceased) for three latitudinally distributed populations of an oviparous lacertid lizard. The experimental results suggested that the mean EAHT decreased with decreasing latitude and that the reaction norms of EAHT in relation to developmental temperatures showed \"flat,\" \"bell-shaped,\" and \"decreasing\" patterns at high, medium, and low latitudes, respectively. Based on the means and plasticity of EAHT and weather data across China, we project that the heat stress frequency would increase from the present to the future and increase toward low latitudes. Furthermore, heat stress becomes more extensive with the incorporation of developmental plasticity. Incorporating the mean EAHT during the embryonic development season, heat stress frequency, and climate variables in a species distribution model projects that suitable habitats could move northward in response to ongoing climate change and shrink due to the loss of southern habitat. More-over, even lizards within the areas that are predicted to remain highly suitable are expected to experience increases in heat stress over time, particularly at medium and low latitudes. Our study reveals geographic variation in the mean and developmental plasticity of EAHT and highlights its importance for predicting species vulnerability and range shifts in response to climate change.

We present the observed area changes in 5234 glaciers (out of which 3435 are debris-free) of Himalaya–Karakoram (H–K) region, mapped at a scale of 1 : 25,000 using primarily IRS LISS III data between the years 2001 and 2016/2017/2018. Area change is a direct observable parameter in the monitoring of glaciers. The mapping results have been analysed in different sectors of H–K region. In the Karakoram region, 2143 glacier bodies with an area coverage of 18343.39 km² show a gain of 0.026%, whereas in Himalayan region, 3091 glaciers covering an area of 11451.53 km² show a loss of 1.44% over a span of 17 years. Loss in glacier area in Himalayan region varies from 0.76% in subbasins located in the left side of NW flowing Indus River (N–W Himalaya/J&K and Ladakh), 2.2% in Chenab and Sutlej basins (Western Himalaya/Himachal Pradesh), 0.84% in Ganga basin (West-Central Himalaya/Uttarakhand), 2.16% in Ganga basin (Central Himalaya/Nepal and a few glaciers of Tibetan region) and 2.15% in Tista sub-basin (Eastern Himalaya/Sikkim). The mapping uncertainty is less than 0.01%. The results also show that debris free glaciers are more vulnerable to global warming thereby affirming the earlier theories of differential impact of warming on debris free and debris covered glaciers. Overall, the statistics clearly indicate the effect of latitudinal variations on the gain/loss in the area of glaciers from higher to lower latitudes in addition to microclimatic and geomorphological factors.