Tropical Latitudes Research Articles

The analysis of global surface temperature wavelets from 1884 to 2014

In this paper, we sought to investigate the spatial and temporal variability of the global sea surface temperature in the 1884–2014 period, through wavelet analysis. Results for tropical, subtropical, and extratropical areas indicate important oscillations in the 1–12-month and 1–2-, 2–4-, 4–8-, and 8–12-year spectral ranges, as obtained in other studies which used regional mean SST values instead of global gridpoint data with 2.5o resolution, as used in this study. The intraseasonal (1–12 months) and interannual (1–2 years) oscillations are much more evident in the tropical latitudes. On the other hand, lower frequency oscillations (2–4, 4–8, and 8–12 years) are more dominant away from tropical regions. The faster oscillation scale (1–12-month and 1–2- and 2–4-year spectral ranges) SST variance presents negative trends throughout the entire period, while the values associated with the slower oscillation scales (4–8- and 8–12-year spectral ranges) present increasing trends. The reversal of trends for distinct SST spectral ranges over the whole period suggests energy exchanges between distinct oscillatory phenomena. In addition, the energy increase of slower frequencies suggests the prolonged settlement of low-frequency climatic patterns in the future, providing more inertial climatic patterns. The strongest diminishing values of SST variance associated with the higher frequency oscillations were observed in the Atlantic oceanic basins. The strongest increasing values for the lower oscillations, mainly related to the 2–4- and 4–8-year spectral ranges, were observed in the Pacific basins. In general, the Pacific basins are closely correlated with the global mean (0.55 ≤ r ≤ 0.92), compared with the Atlantic (0.31 ≤ r ≤ 0.75) and Indian (0.12 ≤ r ≤ 0.56) basins.

Reproduction of the mangrove species Rhizophora stylosa Griff. at its southern latitudinal limit

A study of reproductive phenology and reproductive performance of the mangrove species Rhizophora stylosa was conducted in three estuaries spanning the southernmost 265 km of its known range on the east Australian coast. The timing of reproductive primordia, buds, flowers, fruit and propagule fall did not differ significantly over the latitudinal range of the study. Peak propagule fall occurred in April after a mean 19–20 months of development, only slightly longer than accounts for tropical latitudes. On average, 2.1% of buds matured to form viable propagules, with an average of 17.2% of buds becoming advanced fruit and 11.9% of advanced fruit becoming mature propagules, which compares well with the ranges published accounts for Australian tropical R. stylosa trees. However, there were relatively few buds per inflorescence on recorded shoots in this study, although formal studies on this in the tropics are absent. Within-site variation in bud and propagule production per shoot was greater than variability between sites in many cases, though our sample size was necessarily low due to the rarity of the trees at the southern limit and the detailed recording method. The species reproduces successfully at its known southern limit, with notable comparability to the eastern Australian Tropics. This suggests there is little thermal limitation on reproduction at the southern limit, where there is evidence of slow spread. “Precocious” reproduction as observed for young R. mangle at range limits in North America was not detected.

Neoproterozoic glacial ages in a nonsmooth conceptual model

There is widespread agreement that ice sheets flowed into the ocean in tropical latitudes at sea level during the Earth’s past. Whether these extreme ice ages were snowball Earth events, with the entire surface covered in ice, or whether ocean water remained ice free in regions about the equator, continues to be controversial. For the latter situation to occur, the effect of positive ice albedo feedback would have to be damped to stabilize an advancing ice sheet shy of the equator. In this paper we analyze a conceptual model comprised of a zonally averaged surface temperature equation coupled to a dynamic ice line equation. This difference equation model is aligned with the cold world of these great glacial episodes through an appropriately chosen albedo function. Using the spectral method, the analysis leads to a nonsmooth singular perturbation problem. The Hadamard graph transform method is applied to prove the persistence of an invariant manifold, thereby providing insight into model behavior. A stable climate state with the ice line resting in tropical latitudes, but with open water about the equator, is shown to exist. Also presented are local smooth and nonsmooth bifurcations as parameters related to atmospheric CO2 concentrations and the efficiency of meridional heat transport, respectively, are varied.

Numerical Evaluation of the Modern and Future Origins of Atmospheric River Moisture over the West Coast of the United States.

Atmospheric rivers are one of the major causes of extreme precipitation and flooding in many regions around the world, and have been found to contribute substantially to global poleward moisture transport. However, the evaporative origin of the moisture in atmospheric rivers remains unclear, at least on climatological time-scales. Here we use the water tracer and water isotope-enabled CAM5 model to examine the moisture sources of atmospheric rivers that impact the West Coast of the United States. The climatological distribution of moisture sources is determined for both the modern-era and for 2100 under an RCP8.5 scenario. It is found that 33 to 53 % of the precipitable water over the West Coast of the United States originates from the Northeast Pacific, in particular the midlatitudes and subtropics, although in JJA more moisture is recycled from continental regions. It is also found that although atmospheric rivers are at least 70 % Northeast Pacific moisture, a significant amount of the moisture is derived from tropical latitudes (>15 % from south of 20° N). It is found that in the warmer 2100 climate there is a 39 % increase in the magnitude of ARs. In this future epoch, moisture is transported from more remote regions for all seasons and for both atmospheric rivers and the average climatology. To provide future observational evidence that this model result is robust, it is shown that water isotopes provide an observational constraint on the moisture transport pathways, and thus the possibility to observe changes in moisture source.

Ecological drivers of testate amoeba diversity in tropical water bodies of central Mexico

Testate amoebae are unicellular organisms characterized by a shell-like test. Due to their potential use as bioindicators (and paleoindicators), these organisms have been increasingly studied in the last decade, particularly in temperate latitudes. This study’s objective was two-fold: to identify the testate amoeba communities sampled from 29 water bodies in Mexico and to determine if their presence and distribution also made them suitable bioindicators for tropical latitudes. A total of 40 taxa were recorded within 12 genera, and six significant variables—oxygen, pH, depth, temperature, conductivity, and total alkalinity—that explained testate amoeba distribution within and among the water bodies were identified through a canonical correspondence analysis. The Q-mode clusters rendered five assemblages, each named after their respective dominant species: 1) Centropyxis aculeata strain “aculeata” assemblage, 2) Difflugia oblonga strain “bryophila” assemblage, 3) Diverse assemblage, 4) Cucurbitella tricuspis assemblage, and 5) Difflugia protaeiformis strain “acuminata” assemblage. We found that Cucurbitella tricuspis and the Difflugia protaeiformis strain “acuminata” have similar ecological preferences to those reported previously for temperate lakes, with the former identified as an indicator of eutrophic environments and the latter as an indicator of low oxygen levels. On the other hand, Centropyxis aculeata strain “aculeata” and Arcella vulgaris seem to indicate adverse conditions, but the source of this environmental stress apparently differs from that reported in temperate latitudes. Although this stress source could not be identified in all cases, our study nonetheless demonstrates that testate amoebae in the water bodies of central Mexico could reveal the presence of environmental stress.

From the High Arctic to the Equator: Do Soil Metagenomes Differ According to Our Expectations?

Comparing the functional gene composition of soils at opposite extremes of environmental gradients may allow testing of hypotheses about community and ecosystem function. Here, we were interested in comparing how tropical microbial ecosystems differ from those of polar climates. We sampled several sites in the equatorial rainforest of Malaysia and Brunei, and the high Arctic of Svalbard, Canada, and Greenland, comparing the composition and the functional attributes of soil biota between the two extremes of latitude, using shotgun metagenomic Illumina HiSeq2000 sequencing. Based upon "classical" views of how tropical and higher latitude ecosystems differ, we made a series of predictions as to how various gene function categories would differ in relative abundance between tropical and polar environments. Results showed that in some respects our predictions were correct: the polar samples had higher relative abundance of dormancy related genes, and lower relative abundance of genes associated with respiration, and with metabolism of aromatic compounds. The network complexity of the Arctic was also lower than the tropics. However, in various other respects, the pattern was not as predicted; there were no differences in relative abundance of stress response genes or in genes associated with secondary metabolism. Conversely, CRISPR genes, phage-related genes, and virulence disease and defense genes, were unexpectedly more abundant in the Arctic, suggesting more intense biotic interaction. Also, eukaryote diversity and bacterial diversity were higher in the Arctic of Svalbard compared to tropical Brunei, which is consistent with what may expected from amplicon studies in terms of the higher pH of the Svalbard soil. Our results in some respects confirm expectations of how tropical versus polar nature may differ, and in other respects challenge them.

Hurting the most vulnerable

Climate Change Impacts The Paris Agreement set a goal of limiting global average anthropogenic climate warming to 1.5°C or less—cooler than the oft-cited target of 2°C that previously had been considered the threshold of dangerous consequences. Is the difference in impacts between the two goals meaningful, and who would be affected most by a failure to stay within the lower limit? King and Harrington find that exceeding the 1.5°C ceiling would affect tropical latitudes—which have a disproportionate share of poor populations—more than higher latitudes. Thus, if ways are not found to meet the global warming targets of the Paris Agreement, then the most vulnerable will experience the greatest consequences. Geophys. Res. Lett. 10.1029/2018GL078430 (2018).

Rapidly diminishing mangrove forests in Myanmar (Burma): a review

Mangroves are a very productive ecosystem found in tropical and subtropical latitudes. Southern and south western coastlines of Myanmar host a large number of mangrove species, many under threat of extirpation. This review analyzes recent changes and the current status of mangrove vegetation along the coastline of Myanmar and key factors causing rapid reduction of mangrove coverage. Remote sensing techniques can be used to improve mangrove mapping and monitoring in Myanmar in the future. Community-based mangrove reforestation has helped restore green coastal areas to some extent, even though there are limitations due to the lack of specific biodiversity in reforested areas. Mangrove ecosystem research, conservation and restoration in Myanmar have gained new momentum after the 2010 political reform. Some urgent measures are still needed for the conservation of rapidly diminishing mangrove forests, as well as improving community-based mangrove reforestation, enhancing biodiversity, implementing sustainable aquaculture, and reinforcing environmental protection laws.

Study of diatom assemblages in Sundarbans mangrove water based on light microscopy and rbcL gene sequencing

Sundarbans, the world's largest mangrove deltaic region, is one of the most productive ecosystems in tropical and subtropical latitudes and also serve as a nursery ground for rich coastal fisheries. In this study, we highlighted diatom assemblages from the Indian part of Sundarbans Biosphere Reserve (SBR) area for the first time based on light microscopy and rbcL gene sequencing and phylogeny. In total, 15 diatom species (11 centric forms and 4 pennate forms) were documented using light microscopy, and 3 major clades of diatoms were detected in rbcL phylogeny. Out of 15 diatom species, 7 were the first record from Sundarbans mangrove water. One of the species, Thalassiosira ferelineata Hasle and Fryxell, was reported for the first time in an Asian mangrove ecosystem based on light microscopy. Our study suggests the importance of establishing cultures and their polyphasic taxonomy are the future necessity to create an authenticated diatom database from mangrove water, which is still overlooked globally.

Interannual changes in zooplankton echo subtropical and high latitude climate effects in the southern East China Sea.

Climate variability plays a central role in the dynamics of marine pelagic ecosystems shaping the structure and abundance changes of plankton communities, thereby affecting energy pathways and biogeochemical fluxes in the ocean. Here we have investigated complex interactions driven a climate-hydrology-plankton system in the southern East China Sea over the period 2000 to 2012. In particular, we aimed at quantifying the influence of climate phenomena playing out in tropical (El Nino 3.4) and middle-high latitudes (East Asia Winter Monsoon, EAWM, and Pacific Decadal Oscillation, PDO) on pelagic copepods. We found that the EAWM and El Nino 3.4 showed a non-stationary and non-linear relationship with local temperature variability. In the two cases, the strength of the relationship, as indexed by the wavelet coherence analysis, decreased along with the positive phase of the PDO. Likewise, the influence of EAWM and El Nino3.4 on copepods exhibited a non-stationary link that changed along with the PDO state. Indeed, copepods and EAWM were closely related during the positive phase, while the link copepods–El Nino 3.4 was stronger during the negative phase. Our results pointed out cascading effects from climate to plankton driven by the positive phase of the PDO through its effect on temperature conditions, and likely through a larger southward transport of nutrient-rich water masses to northern Taiwan and the Taiwan Strait. We suggest a chain of mechanisms whereby the PDO shapes interannual dynamics of pelagic copepods and highlight that these results have implications for integrative management measures, as pelagic copepods plays a prominent role in food web dynamics and for harvested fish in the East China Sea.

Increasing extent and intensity of thunderstorms observed over the Congo Basin from 1982 to 2016

Recent studies found a long-term drought and resulting declines in vegetation greenness and canopy water content over the Congo Basin, the second largest rainforest in the world after the Amazon. Since most precipitation in tropical latitudes stems from convection, this paper analyzed 35 years of high-resolution (8 km spatial resolution and 3 h temporal resolution) satellite data to document the long-term trends in the number, size and intensity of thunderstorms activity over the Congo Basin during April, May, and June (AMJ) for the period 1982–2016. Changes in the magnitude and area of cold cloud top brightness temperatures (Tb) at different thresholds were used as a proxy to quantify the number and size of individual thunderstorms at different intensities. We found that the areal extent and intensity of thunderstorms increased over the past 35 years, particularly over Northern Congo Basin, and these changes are consistent with other satellite datasets. Combined with a reanalysis dataset, our work suggests that thunderstorms over the Congo Basin are becoming taller and wider, and likely resulting in a moister (drier) upper (lower) troposphere.

Global climatology of planetary boundary layer top obtained from multi-satellite GPS RO observations

Accurate estimation of the planetary boundary layer (PBL) top is essential for air quality prediction, weather forecast, and assessment of regional and global climate models. In this article, the long-term climatology of seasonal, global distribution of PBL is presented by using global positioning system radio occultation (GPSRO) based payloads such as Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), Communication/Navigation Outage Forecast System (C/NOFS), TerraSAR-X, and The Gravity Recovery and Climate Experiment (GRACE) from the year 2006–2015. We used Wavelet Covariance Transform (WCT) technique for precise PBL top identification. The derived PBL top from GPSRO data is rigorously evaluated with GPS radiosonde data over Gadanki. Significant seasonal variation is noticed in both radiosonde and GPSRO observations. Further, we compared the PBL obtained GPS RO with global radiosonde network and observed very good correlation. The number of occultations reaching down to 500 m and retrieval rate of PBL top from WCT method is very high in mid-latitudes compared to tropical latitudes. The global distribution of PBL top shows significant seasonal variation with higher during summer followed by spring, fall, and minimum in winter. In the vicinity of Inter Tropical Convergence Zone (ITCZ), the PBL top is high over eastern Pacific compared to other regions. The ERA-Interim reanalysis data underestimate the PBL top compared to GPS RO observations due to different measurement techniques. The seasonal variation of global averaged PBL top over land and ocean shows contrasting features at different latitude bands.

Two new macraucheniids (Mammalia: Litopterna) from the late middle Miocene (Laventan South American Land Mammal Age) of Quebrada Honda, Bolivia

ABSTRACT We describe two new macraucheniid litopterns from the late middle Miocene (ca. 13 Ma) Quebrada Honda Fauna of southern Bolivia. The holotype of ‘Theosodon’ arozquetai, sp. nov., is a partial cranium preserving RI2–M3 and LP1–M3, elements of the hind limb, and two metapodials. An upper cheek tooth series is also referred to this species. The holotype of Llullataruca shockeyi, gen. et sp. nov., is a mandible preserving nearly the entire lower dentition. A dentary, several upper teeth, and a variety of postcranial elements are also referred to this species. Two specimens from the slightly older locality of Cerdas, Bolivia, are assigned to L. cf. shockeyi. A phylogenetic analysis recovers ‘T.’ arozquetai as sister to Theosodon spp., and we provisionally refer it to that genus pending its revision. Llullataruca shockeyi forms a polytomy with three late Oligocene–early Miocene ‘cramaucheniines’ and the later-diverging macraucheniids. The body mass of ‘T.’ arozquetai is estimated at 80.8–116.2 kg, slightly smaller than early Miocene T. garretorum. Llullataruca shockeyi is among the smallest known macraucheniids based on dental dimensions and is estimated at 35.3–54.6 kg. Theosodon' arozquetai and L. shockeyi are the first well-characterized macraucheniids from the middle Miocene, and the latter species demonstrates that relatively early-diverging lineages persisted at least 7 million years longer in tropical latitudes than they did in Patagonia. http://zoobank.org/urn:lsid:zoobank.org:pub:D26BB67B-D8E1-4D36-9552-4391874CF69C SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: McGrath, A. J., F. Anaya, and D. A. Croft. 2018. Two new macraucheniids (Mammalia: Litopterna) from the late middle Miocene (Laventan South American Land Mammal Age) of Quebrada Honda, Bolivia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1461632.

Phenotypic plasticity of life-history traits of a calanoid copepod in a tropical lake: Is the magnitude of thermal plasticity related to thermal variability?

According to the Climatic Variability Hypothesis [CVH], thermal plasticity should be wider in organisms from temperate environments, but is unlikely to occur in tropical latitudes where temperature fluctuations are narrow. In copepods, food availability has been suggested as the main driver of phenotypic variability in adult size if the range of temperature change is less than 14°C. Leptodiaptomus garciai is a calanoid copepod inhabiting Lake Alchichica, a monomictic, tropical lake in Mexico that experiences regular, narrow temperature fluctuations but wide changes in phytoplankton availability. We investigated whether the seasonal fluctuations of temperature and food produce phenotypic variation in the life-history traits of this tropical species. We sampled L. garciai throughout a year and measured female size, egg size and number, and hatching success, along with temperature and phytoplankton biomass. The amplitude of the plastic responses was estimated with the Phenotypic Plasticity Index. This index was also computed for a published dataset of 84 copepod populations to look if there is a relationship between the amplitude of the phenotypic plasticity of adult size and seasonal change in temperature. The temperature annual range in Lake Alchichica was 3.2°C, whereas phytoplankton abundance varied 17-fold. A strong pattern of thermal plasticity in egg size and adult female size followed the inverse relationship with temperature commonly observed in temperate environments, although its adaptive value was not demonstrated. Egg number, relative reproductive effort and number of nauplii per female were clearly plastic to food availability, allowing organisms to increase their fitness. When comparing copepod species from different latitudes, we found that the magnitude of thermal plasticity of adult size is not related to the range of temperature variation; furthermore, thermal plasticity exists even in environments of limited temperature variation, where the response is more intense compared to temperate populations.

Phenotypic plasticity in the timing of reproduction in Andean bears

AbstractMany factors influence whether mammals reproduce seasonally or continuously but disentangling them can be challenging in free‐living species that are hard to observe. We described the seasonality of reproduction in Andean bears (Tremarctos ornatus) in NW Peru (6°26′S, 79°33′W) to test for phenotypic plasticity in response to extrinsic cues. To do so, we compared the mating behavior and birthdates of free‐living bears to the birthdates of captive bears housed over a broad range of latitudes. Free‐living bears were observed on 302 occasions over 6 years (967 field‐days), and mating behaviors recorded 61 times from late Dec to Jan. The mean birthdate of 12 wild‐born litters was 17 August (range = 23 Jun – 15 Oct), 57 ± 10 (SD) days after the winter solstice. Birthdates for 367 captive litters varied widely by comparison (range = 1 Jan – 31 Dec; mean = 14 ± 49 days after the winter solstice). However, captive bears in the tropics had fewer births in autumn and winter (71.4% of births) than captive bears at higher latitudes (96.8% of births; P < 0.001). Differences in seasonal reproduction among captive bears at high and low latitudes and captive and a free‐living at tropical latitudes suggest that Andean bears display phenotypic plasticity in reproductive timing but influenced by photoperiod at high latitudes. Because photoperiodic effects were less evident at tropic latitudes, we suggest that seasonality in the timing of reproduction in the free‐living bears we observed was influenced by seasonal variation in food abundance. The observed effect of photoperiod on reproduction in captive Andean bears at high latitudes may also imply that free‐living bears at the southern edge of the range may be constrained in their ability to adjust reproductive timing to resource availability as environments change.

Phylogenetic uniqueness, not latitude, explains the diversity of avian blood parasite communities worldwide

AbstractAimCharacterizing macroecological patterns in biodiversity is key to improve our understanding of community assembly. Global biodiversity for many taxa follows a latitudinal gradient, with increased diversity in tropical latitudes. Less is known about global parasite biodiversity, inhibiting our ability to predict how global change will impact parasitic disease emergence. Using distribution and phylogenetic data for 2,386 avian haemosporidian blood parasites (genera Plasmodium, Haemoproteus and Leucocytozoon), I assessed how contemporary and historical drivers influence the composition of parasite communities worldwide.LocationGlobal.Time periodCurrent.Major taxa studiedHaemosporidian blood parasites.MethodsParasite distribution and cytochrome b sequence data were accessed from an open‐source database. Bayesian phylogenetic tree distributions were constructed for each parasite genus using two substitution models to capture uncertainty. Hierarchical regressions assessed effects of environmental variation, latitude and phylogenetic β‐diversity (βdiv; a proxy for phylogenetic uniqueness) on the diversity and asymmetry of parasite communities around the globe.ResultsI uncovered biodiversity hotspots and identified broad variation in global diversity patterns among parasite genera. Community diversity increased with increasing phylogenetic uniqueness for all three parasite genera; however, these diverse and unique regions did not consistently occur in the tropics. I found no evidence of a latitudinal diversity gradient, and support for a latitudinal gradient in community phylogenetic asymmetry was weak.Main conclusionsGlobal variation in avian haemosporidian phylogenetic diversity does not reflect a latitudinal gradient. Instead, parasite biogeography may reflect fundamental differences in host‐switching tendencies or the timing of avian evolutionary radiations. Examining the interplay between shared evolutionary history and phylogenetic diversity can provide important insights into the drivers of parasite biodiversity at global scales.

Can 'loss and damage' carry the load?

Even assuming a heroic rush towards carbon reduction and adaptation, some regions of the world will be hammered hard by climate impacts. Thus, a global consensus now sees the need for a supplemental plan to deal with the kind of harms that cannot be avoided-what Parties call 'loss and damage'. For a loss-and-damage plan to work, it must be capable of carrying the load, the load being whatever minimal standards that morality and political consensus require. But if residual risk climbs too high, it will fall short of even the most basic expectations. The Paris Agreement calls for holding the rise in global average temperature to 'well below 2°C above pre-industrial levels', while working to limit the increase to 1.5°C. How much difference is in that half-degree? From the point of view of residual risk, quite a lot. According to a 2016 study published by the European Geosciences Union, a jump from 1.5°C to 2°C could produce outsize impacts, particularly in tropical latitudes. That difference could mark the line between a plan that is politically and morally defensible and one that is not. At the very least, the difference is enough to inform the design and expectations of any future plan.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

Duration of embryo development and the prevalence of haematozoan blood parasites in birds

ABSTRACT We used the prevalence of avian haemosporidian blood parasites (Plasmodium and Haemoproteus), quantified by PCR screening and DNA sequencing, to reevaluate a previously described negative relationship, based on microscopic examination of blood smears, between the prevalence of parasites in an avian host population and the length of the embryo development period of the host species. Analyses were restricted to small land birds in continental areas of the Americas. Prevalence determined by DNA methods averaged 22.5% and did not differ between tropical and temperate latitudes. Compared across taxonomic families or subfamilies, parasitism levels obtained by microscopic examination of blood smears and by DNA methods were strongly correlated and decreased, similarly in tropical and temperate latitudes, with increasing length of the embryo development period. Understanding the association of reduced haemosporidian infection with prolonged embryo development remains a fundamental challenge that emphasize...

First adequately-known quadrupedal sirenian from Eurasia (Eocene, Bay of Biscay, Huesca, northeastern Spain)

Sirenians are the only extant herbivorous mammals fully adapted to an aquatic lifestyle. They originated in Africa during the Paleocene from an undetermined clade of afrotherian mammals, and by the end of the Eocene they were widely distributed across the tropical latitudes. Here we introduce Sobrarbesiren cardieli gen. et sp. nov. It is the first adequately-known quadrupedal sirenian from Eurasia and the oldest record of this clade from western Europe. Fossils have been recovered from the middle Lutetian (SBZ15) site of Castejón de Sobrarbe-41 (Huesca, Spain), and comprise many cranial and postcranial remains, including pelvic girdle and hind limb bones, from at least six sirenian individuals of different ontogenetic stages. Sobrarbesiren shows a suite of characters previously considered synapomorphies of different clades of derived sirenians, such as the presence of the processus retroversus of the squamosal and the pterygoid fossa, combined with ancestral characters such as the presence of an alisphenoid canal, a permanent P5, at least two sacral vertebrae, a primitive pelvis and functional femora and fibulae. Sobrarbesiren is recovered as the sister taxon of Dugongidae and represents a transitional stage of adaptation to aquatic life between the amphibious quadrupedal prorastomids and the aquatic quadrupedal protosirenids.

Geographical variation and local environment effects in the reproductive output and fecundity of the shrimp Exhippolysmata oplophoroides (Decapoda: Caridea) in southeastern Brazil

We studied the shrimp Exhippolysmata oplophoroides in southeastern Brazil (Macaé, 22º37″S; Ubatuba, 23º55″S; and Cananéia, 25º53″S) to test the hypotheses that (1) females should have the same reproductive output and fecundity at the regional scale, and (2) these reproductive parameters can vary among regions. Maximum carapace length (Macaé = 13.1 mm, Ubatuba = 12.8, Cananéia = 16), fecundity, and reproductive output differed among regions (Ancova, p < 0.05). Females in Cananéia exhibited the highest reproductive output/fecundity (18.6%/5230 embryos), followed by those in Macaé (16.0%/4365 embryos) and Ubatuba (12.6%/1206 embryos). We found that fecundity/reproductive output varies inversely with the length of the reproductive season, i.e. a considerable amount of energy is allocated during seasonal spawning periods in subtropical regions such as Cananéia. Previous studies have proved that E. oplophoroides is able to reproduce continuously in Ubatuba, with probably minor but continuous energy investment in reproduction occurring in this tropical region. In contrast, although Macaé is located at tropical latitude, it is under the influence of Cabo Frio upwelling that alters the water’s physical properties via cold water intrusion. This process may be a determining factor in the spawning seasonality of Macaé’s shrimp population, justifying the higher reproductive output recorded here than in Ubatuba.