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1.
Lee G. Miles Stacey L. Lance Sally R. Isberg Chris Moran Travis C. Glenn 《Conservation Genetics》2009,10(4):935-954
Microsatellite DNA loci have emerged as the dominant genetic tool for addressing questions associated with genetic diversity
in many wildlife species, including crocodilians. Despite their usefulness, their isolation and development can be costly,
as well as labour intensive, limiting their wider use in many crocodilian species. In this study, we investigate the cross-species
amplification success of 82 existing microsatellites previously isolated for the saltwater crocodile (Crocodylus porosus) in 18 non-target crocodilian species; Alligator sinensis, Caiman crocodylus, Caiman latirostris, Caiman yacare, Melanosuchus niger, Paleosuchus palpebrosus, Crocodylus acutus, Mecistops cataphractus, Crocodylus intermedius, Crocodylus johnstoni, Crocodylus mindorensis, Crocodylus moreletii, Crocodylus niloticus, Crocodylus novaeguineae, Crocodylus palustis, Crocodylus rhombifer, Crocodylus siamensis, and Osteolaemus tetraspis. Our results show a high level of microsatellites cross-amplification making available polymorphic markers for a range of
crocodilian species previously lacking informative genetic markers. 相似文献
2.
All crocodilians are under varying degrees of threat due to over exploitation and these species have been listed in Appendix
I or II of CITES. The lack of molecular techniques for the identification of confiscated samples makes it difficult to enforce
the law. Conclusive forensic identification of species requires a complete gene sequence which is difficult in case of degraded
samples. We have developed two novel sets of primers to amplify two partial cytochrome b gene sequences of six crocodile species i.e. Crocodylus palustris, Crocodylus porosus, Crocodylus siamensis, Crocodylus niloticus, Gavialis gangeticus and Caiman crocodilus. These partial sequences were edited to give a complete cyt b gene sequence, which can be used as an effective tool for forensic authentication of crocodile species. A phylogeny of crocodile
species was reconstructed using these sequences. The described primers hold great promise in forensic identification of crocodile
species, which can aid in the effective enforcement of law and conservation of these ancient species. 相似文献
3.
S. Pidcock L. E. Taplin G. C. Grigg 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(2):153-158
Major electrolytes and nitrogenous excretory products were analysed in the blood plasma, ureteral urine and cloacal urine
of juvenile Alligator mississippiensis and Crocodylus porosus in fresh and hypoosmotic salt water (206 mosmol · l−1). Both species coped well with saline water, showing little (Alligator) or no (Crocodylus) change in plasma composition. Comparisons of renal-cloacal function point to major differences in their osmoregulatory physiology.
The cloaca of C. porosus is a very active osmoregulatory organ in salt and fresh water, contributing to water conservation and NaCl excretion through
the lingual salt glands. In contrast, the cloaca of Alligator has little impact on the composition of excreted urine. It seems likely that A.␣mississippiensis is largely constrained to a renal response to osmotic and ionic stress while C. porosus is able to call on a more complex mix of renal response, post-renal modification of urine in the cloaca, and excretion of
excess NaCl through the salt glands. The results support the idea that there are deep-seated differences in the osmoregulatory
physiology of alligatorids and crocodylids (Eusuchia), an understanding of which should provide valuable insights into their
evolution and zoogeography.
Accepted: 7 September 1996 相似文献
4.
5.
G. C. Grigg L. A. Beard T. Moulton M. T. Queirol Melo L. E. Taplin 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(6):445-452
The broad-snouted caiman Caiman latirostris, of South America mostly frequents freshwater but occurs also in estuaries. Nothing of substance is known of its osmoregulatory
physiology but, in the light of accumulating evidence that alligatorids lack specialised adaptations for life in hyperosmotic
waters, we anticipated its physiology would be more similar to that of Alligator mississippiensis than the euryhaline Crocodylus porosus, which has both lingual salt glands and a more complex renal:cloacal system. This proved to be the case. Caiman captured
in estuaries of the Ilha do Cardoso in southern Brazil were effective hypo-osmotic osmoregulators in salinities of 0–24 ppt
(seawater = 35 ppt). Plasma osmolarity, sodium and chloride were similar to those in other crocodilians and not influenced
by salinity. Plasma urea was low and did not vary with salinity. We found no evidence of lingual or other salt glands. Urinary
electrolyte concentrations varied considerably with salinity and in ways reminiscent of A. mississippiensis but very different from C. porosus.
Ca. latirostris dehydrated in seawater more rapidly than C. porosus and had substantially higher integumental permeability to water. Caiman did not drink seawater but rehydrated rapidly when
returned to freshwater (FW). We found small caiman (<500 g) only in very low salinities (<3 ppt) and larger caiman closer
to the sea. We postulate that medium to large Ca. latirostris can take advantage of the feeding opportunities presented by the estuarine mangal despite lacking the physiological specialisations
of crocodylids. Two individuals which we re-sighted by chance had travelled at least 600 m in 2–3 days, showing that every
caiman we captured or saw was within easy reach of FW. Most likely their habitation of the estuary and its mangal is achieved
through a combination of low surface area:volume ratio, relatively impermeable skin, and periodic access to FW.
Accepted: 11 May 1998 相似文献
6.
Miguel Moreno-Azanza Blanca Bauluz José I. Canudo Eduardo Puértolas-Pascual Albert G. Sellés 《Historical Biology》2014,26(2):195-205
The Upper Cretaceous outcrops of the Pyrenees yield one of the most extensive and continuous records of paleoological remains anywhere in the world. Most of eggs and eggshells have been referred to the oofamily Megaloolithidae. In this study, we present a revision of eggshell fragments from the Blasi 2 locality, lattermost Maastrichtian in age, previously assigned to aff. Megaloolithidae. The presence of a blocky extinction pattern and basal knobs supports a crocodilian affinity of these materials. We classify them as Krokolithidae indet. Three structural layers can be recognised in the Blasi 2 eggshells, a feature that is shared with other recent eggshells (e.g. Crocodylus porosus and Crocodylus niloticus) and fossil crocodylomorph eggshells (Krokolitheswilsoni), which were previously described as single layered. The new proposed affinity of the Blasi 2 eggshells reduces the Megaloolithidae oodiversity of the last few million years of the Cretaceous in the Pyrenees to only two valid ootaxa, Megaloolithusmamillare and Megaloolithusbaghensis. The lack of more complete material precludes the erection of new ootaxa based on the Blasi 2 material. 相似文献
7.
Bernat Vila Diego Castanera Josep Marmi José I. Canudo Àngel Galobart 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2015,48(2):256-266
Recently discovered evidence of tracks in the continental beds of the Late Cretaceous Tremp Formation in the southern Pyrenees (NE Iberian Peninsula) has been identified as scratch marks made by buoyant crocodiles. The tracks are preserved in two distinct environments and substrates (marly limestones originating in a littoral mud flat and fine‐grained sandstones deposited in fluvial settings). Most of the crocodylian traces are ascribed to ichnogenus Characichnos, whereas a single plantigrade pes track is assigned to ichnogenus cf. Crocodylopodus. The crocodylian swim traces (Characichnos ichnofacies) found in the early and late Maastrichtian co‐occur with Brontopodus ichnofacies attributable to terrestrial tetrapods (titanosaur sauropods, cf. Brontopodus ichnogenus; and hadrosaurid ornithopods, Hadrosauropodus ichnogenus). Analysis of the tracks allows the interpretation of palaeoenvironmental settings and track production. Thus, in lagoonal environments, swim tracks of crocodylians were produced during the rise of the water level in successive tide cycles; in fluvial settings, the swim traces of crocodylians were produced within the channel at the low‐water stage. To date, there are no reports of Late Cretaceous crocodylian tracks in Europe, and the studied evidence represents the first and youngest track record of the group in the latest part of the Cretaceous (C29r) in this continent and probably in the world. 相似文献
8.
Osmoregulation in Crocodilians 总被引:1,自引:0,他引:1
Recent crocodilians live primarily in freshwater habitats. Howevertwo species (Crocodylus acutus and C. porosus) are estuarinespecialists; two others (C. niloticus and C. johnstoni) thatare primarily found in fresh water, have estuarine populations.Routes of uptake of water and sodium include drinking, feedingand associated incidental drinking, and integumental and buccaldiffusion. Routes of loss include faeces-cloacal fluid, lingualsalt glands, integumental and buccal diffusion, and respiratoryloss. The least understood route of salt and water exchangeis that of the oral and buccal epithelia, which are much morepermeable to water and sodium than the general integument. Thefreshwater alligator (Alligator mississippiensis) osmoregulatesin a manner typical for an amphibious reptile. Body sodium turnoveris low and the general integument is quite low in permeabilityto sodium. Water turnover is more rapid (in terms of molar exchange)but still relatively low for an aquatic reptile. Most waterexchange occurs across the integument and buccal epithelia.The presence of lingual salt glands in freshwater crocodiliansremains enigmatic, as does the failure of these exocrine glandsin estuarine species to respond to saline loading. Secretiondoes occur after injection of the parasympathetic stimulantmethacholine chloride. The "salt water crocodile" (C. porosus)possesses a suite of osmoregulatory adaptations similar to thosefound in other estuarine reptiles. Water and sodium balanceare maintained primarily by an extremely low general permeabilityto sodium, by economies in water loss, and by excretion of excesssodium by the lingual salt glands. Further work is needed toexamine newly hatched C. porosus, and the possibility of ontogeneticchange in lingual gland function in C. acutus. The importanceof incidental drinking of sea water during feeding (recentlydiscovered in turtles) needs to be evaluated in crocodilians.The use of osmoregulatory data in interpretation of the evolutionaryhistory of the genus Crocodylus needs to be viewed with caution.The hypothesis that all species of Crocodylus originated fromthe transoceanic migration of a saline-tolerant form may notbe the most parsimonious explanation. 相似文献
9.
10.
A diagnosis of crocodile feeding traces on larger mammal bone, with fossil examples from the Plio-Pleistocene Olduvai Basin, Tanzania 总被引:1,自引:0,他引:1
Neotaphonomic studies have determined the patterns of bone damage created by larger mammalian carnivores when consuming mammalian carcasses. Typically, mammalian carnivores gnaw and break bones to various degrees in order to access marrow, grease, and brain tissue. In contrast, crocodiles attempt to swallow whole parts of mammal carcasses, inflicting in the process tooth marks and other feeding traces on some of the bones they are unable to ingest. Although crocodiles are major predators of larger mammals along the margins of protected tropical rivers and lakes, their feeding traces on bone have received little systematic attention in neotaphonomic research. We present diagnostic characteristics of Crocodylus niloticus damage to uningested mammal bones resulting from a series of controlled observations of captive crocodile feeding. The resulting bone assemblages are composed of primarily complete elements from articulating units, some of which bear an extremely high density of shallow to deep, transversely to obliquely oriented tooth scores over often large areas of the bone, along with shallow to deep pits and punctures. Some of the tooth marks (bisected pits and punctures, hook scores) have a distinctive morphology we have not observed to be produced by mammalian carnivores. The assemblages are also characterized by the retention of both low- and high-density bone portions, an absence of gross gnawing, and minimal fragmentation. Together, the damage characteristics associated with feeding by crocodiles are highly distinctive from those produced by mammalian carnivores. Modern surface bone assemblages along the Grumeti River in Tanzania's Serengeti National Park contain a mixture of specimens bearing damage characteristic of crocodiles and mammalian carnivores. Comparison of Plio-Pleistocene fossil bones from Olduvai Gorge, Tanzania, to bones damaged by captive and free-ranging Nile crocodiles reveals direct evidence of fossil crocodilian feeding from larger mammal bones associated with Oldowan stone artifacts. 相似文献
11.
M. A. Russello P. Brazaitis J. Gratten G. J. Watkins-Colwell A. Caccone 《Conservation Genetics》2007,8(4):777-787
The saltwater crocodile (Crocodylus porosus) is the largest and most broadly distributed crocodilian species, and thus is of special conservation and economic interest.
Similar to other parts of its range throughout the Indo-Pacific, C. porosus distributed in the Republic of Palau have experienced a severe population decline over the past century primarily due to
commercial hunting and eradication campaigns. In addition, several thousand crocodiles of undocumented species and origin
were imported into Palau during the 1930’s for commercial farming purposes, potentially polluting the gene pool of the endemic
saltwater crocodiles. Analysis of 39 individuals collected throughout the Republic of Palau revealed a single mitochondrial
DNA control region haplotype shared by populations sampled in Sulawesi, Borneo and Australia. The mtDNA results, in combination
with microsatellite genotypic data at six loci, detected no evidence for inter-specific hybridization between endemic Palauan
C. porosus and potentially introduced Crocodylus species. There was no evidence for a genetic bottleneck in the Palauan population, however an excess of rare alleles was
identified, indirectly suggesting a recent history of admixture potentially linked to introductions of non-native C. porosus. Following from these findings, Palauan C. porosus should be included in the single ESU previously established for all saltwater crocodiles given the recovery of a fixed, but
geographically widespread haplotype. Although Palauan C. porosus exhibited significant genetic differentiation relative to all other sampled populations, it’s delineation as a distinct management
unit is precluded at the present time by evidence that the genetic integrity of the population may have been compromised by
the introduction of non-native saltwater crocodiles. 相似文献
12.
Renivermis crocodyli, n. g., n. sp., is described from the kidneys of the saltwater crocodileCrocodylus porosus Schneider from northern Australia. The genusRenivermis is grouped withExotidendrium Mehra, 1935 andSimhatrema Chattopadhyaya, 1970 in the family Exotidendriidae Mehra, 1935. An amended diagnosis of the family and a key to its genera are given. 相似文献
13.
John Eme Tomasz Owerkowicz June Gwalthney Jason M. Blank Bryan C. Rourke James W. Hicks 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2009,179(8):921-931
The oxygen transport system in mammals is extensively remodelled in response to repeated bouts of activity, but many reptiles
appear to be ‘metabolically inflexible’ in response to exercise training. A recent report showed that estuarine crocodiles
(Crocodylus porosus) increase their maximum metabolic rate in response to exhaustive treadmill training, and in the present study, we confirm
this response in another crocodilian, American alligator (Alligator mississippiensis). We further specify the nature of the crocodilian training response by analysing effects of training on aerobic [citrate
synthase (CS)] and anaerobic [lactate dehydrogenase (LDH)] enzyme activities in selected skeletal muscles, ventricular and
skeletal muscle masses and haematocrit. Compared to sedentary control animals, alligators regularly trained for 15 months
on a treadmill (run group) or in a flume (swim group) exhibited peak oxygen consumption rates higher by 27 and 16%, respectively.
Run and swim exercise training significantly increased ventricular mass (~11%) and haematocrit (~11%), but not the mass of
skeletal muscles. However, exercise training did not alter CS or LDH activities of skeletal muscles. Similar to mammals, alligators
respond to exercise training by increasing convective oxygen transport mechanisms, specifically heart size (potentially greater
stroke volume) and haematocrit (increased oxygen carrying-capacity of the blood). Unlike mammals, but similar to squamate
reptiles, alligators do not also increase citrate synthase activity of the skeletal muscles in response to exercise. 相似文献
14.
Srikulnath K Thongpan A Suputtitada S Apisitwanich S 《Molecular biology reports》2012,39(4):4709-4717
Based on molecular phylogeny of available complete mitochondrial DNA (mtDNA) genome sequences reveals that Crocodylus siamensis and C. porosus are closely related species. Yet, the sequence divergence of their mtDNA showed only a few values under conspecific level.
In this study, a new haplotype (haplotype2, EF581859) of the complete mtDNA genome of Siamese crocodile (C. siamensis) was determined. The genome organization, which appeared to be highly similar to haplotype1 (DQ353946) mtDNA genome of C. siamensis, was 16,814 bp in length. However, the sequence divergence between the two genomes differed by around 7–10 and 0.7–2.1% for
the haplotype1 between C. siamensis and C. porosus (AJ810453). These results were consistent with the phylogenetic relationship among the three genomes, suggesting that C. siamensis haplotype1 mtDNA genome might be the hybrid or the intraspecific variation of C. porosus. On the other hand, our specimen was found to be a true C. siamensis. Simultaneously, the seven species-specific DNA markers designed based on the distinctive site between haplotype2 mtDNA sequences
of C. siamensis and haplotype1 mtDNA sequence of C. siamensis–C. porosus were successfully used to distinguish C. siamensis from C. porosus. These effective markers could be used primarily for rapid and accurate species identification in population, ecology and
conservation studies. 相似文献
15.
Recent phylogenetic analyses of fossil and living crocodyliansallow us to compare the taxonomic, geographic, and temporaldistributions of morphological features, such as snout shapes.A few basic snout morphotypesgeneralized, blunt, slender,deep, and excessively broad ("duck-faced")occur multipletimes in distantly-related lineages. Some cladesespeciallythose found in the Northern Hemisphere or with minimum originationdates in the Cretaceous or lower Tertiaryare morphologicallyuniform, but geographically widespread; crocodylian faunas ofthe early Tertiary tend to be composite, with sympatric taxabeing distantly related, and similar-looking taxa on differentcontinents being close relatives. In contrast, crocodylian faunasof the later Tertiary tend to be more endemic, with local adaptiveradiations occurring in Africa and Australia containing membersof most basic snout shapes. Endemic radiations in Africa andAustralia have largely been replaced by Crocodylus, which canbe divided into subclades that may individually represent endemicadaptive radiations. 相似文献
16.
James O. Farlow Nathan J. Robinson Cory J. Kumagai Frank V. Paladino Peter L. Falkingham Ruth M. Elsey 《Ichnos》2018,25(1):30-65
We documented trackways of free-living Crocodylus acutus on beaches at the mouths of Tamarindo and Ventanas estuaries, Costa Rica. Our crocodiles had estimated total lengths of 1–3 meters or more. Manus prints have five digits, with digits I–III bearing claw marks. Pes prints have four digits, with claw marks on digits I–III. The pes is plantigrade. Claws generally dig into the substrate. Apart from claw marks, digit I and the heel of the pes are usually the most deeply impressed parts of footprints. Trackways are wide-gauge. Pes prints are usually positioned just behind ipsilateral manus prints of the same set and may overlap them. Manus and pes prints angle slightly outward with respect to the crocodile's direction of movement. Claw-bearing digits of both the manus and pes may create curved, concave-toward-the-midline drag marks as the autopodium is protracted. The tail mark varies in depth and clarity, and in shape from nearly linear to markedly sinuous. Sometimes the tail mark hugs the trackway midline, but sometimes it is closer to, or even cuts across, prints of one side. American crocodile footprints and trackways are similar to those observed in other extant crocodylian species, indicating substantial trackway conservatism across the group. 相似文献
17.
MASSIMO DELFINO MADELAINE BÖHME LORENZO ROOK 《Zoological Journal of the Linnean Society》2007,149(3):293-307
It is generally assumed that the Neogene crocodylian fauna of Europe has been represented only by brevirostrine alligatoroid Diplocynodon and longirostrine false gharials ( Gavialosuchus and/or Tomistoma ), which became extinct prior to 6 Mya. Although several lines of evidence suggest that Crocodylus originated in Africa during the Miocene and then promptly dispersed to other continents, the occurrence of this genus in Europe has never been rigorously proven and the traditional palaeontological approach failed to identify a monophyletic group of fossil Crocodylus (simply leading to a proliferation of extinct taxa). The new remains reported here, from an endemic insular fauna from southern Italy, Late Messinian to earliest Pliocene in age (5–6 million years old), represent the youngest European crocodylian, and allow, for the first time in a phylogenetic context, an unambiguous demonstration that Crocodylus dispersed into Europe, possibly during the Tortonian. If the peculiar morphology of the medial maxillary edge is interpreted as evidence for a medial dorsal boss, the southern Italian Crocodylus could be related to C. checchiai from the late Neogene of Libya. The presence of this African immigrant in Europe confirms the role of climate change for faunal dispersal and island colonization. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 293–307. 相似文献
18.
Tobias B. Grun 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2016,49(3):285-286
Stingrays (Order: Myliobatiformes) are well‐known predators that feed on a variety of marine species including crustaceans, teleosts, molluscs and annelids. Here, a predatory attack by a stingray on the large spatangoid echinoid Meoma ventricosa (Lamarck) is reported from the shallow‐water carbonate platform of San Salvador, Bahamas. A single stingray was observed feeding on a large adult specimen of M. ventricosa near Sand Dollar Beach, San Salvador Island. The partially crushed and partially eviscerated test of the attacked echinoid was collected from the feeding site. In addition, a crushed test of a freshly killed, smaller irregular clypeasteroid echinoid Leodia sexiesperforata (Leske) was also recovered at the same site. In both cases, the test was broken across the test plates and not along plate boundaries. Meoma ventricosa showed major plate loss on the oral side; however, bite traces and spine loss were not observed in the damaged areas. Similarly, L. sexiesperforata showed no evidence of spine removal; however, bite marks were identifiable. The observed test damage in both taxa is morphologically distinct and could be potentially identifiable in the fossil record. 相似文献
19.
Effects of Incubation Temperature on Crocodiles and the Evolution of Reptilian Oviparity 总被引:1,自引:0,他引:1
Crocodylus porosus is a mound-nesting crocodilian in which incubationtemperature influences the rate of embryonic development, theprobability that embryos will survive to hatching, post-hatchinggrowth rates and the probability of hatchlings surviving to2 yr of age. Similar responses have been described in Alligatormississippiensis (Joanen et al., 1987) and C. niloticus (Hutton,1987), and they reflect a suite of "non-sexual" effects of incubationtemperature. Temperature-dependent sex determination allocatessex on the basis of these "non-sexual" effects. In C. porosus,it results in maleness being assigned to embryos with high probabilitiesof surviving and good potential for post-hatching growth. Withinthe limits of survival, effects of the moisture environmenton embryological development rate and hatchling fitness seemminor relative to those of the temperature environment. Reptilian orders have either obligate oviparity (chelonians,crocodilians and rhynchocephalians) or facultative oviparity(squamates), depending on the extent of embryonic developmentwithin the oviducts. The distinction is equally one betweenembryos which are buffered from thermal effects within a female'sbody (facultative oviparity) and those that are not (obligateoviparity). Facultative oviparity and internal thermal bufferingmay be the primitive condition within the Class Reptilia, andthe "shell-less" eggs of extant squamates may reflect the originalamniote egg. Obligate oviparity, which also exists in birds,appears to have been a specialized development, and is a blindend in the evolution of viviparity among vertebrates. The significanceof thermal buffering being lost in obligate oviparous reptilesremains unclear. 相似文献
20.
Oaks JR 《Evolution; international journal of organic evolution》2011,65(11):3285-3297
True crocodiles (Crocodylus) are the most broadly distributed, ecologically diverse, and species-rich crocodylian genus, comprising about half of extant crocodylian diversity and exhibiting a circumtropical distribution. Crocodylus traditionally has been viewed as an ancient group of morphologically conserved species that originated in Africa prior to continental breakup. In this study, these long-held notions about the temporal and geographic origin of Crocodylus are tested using DNA sequence data of 10 loci from 76 individuals representing all 23 crocodylian species. I infer a time-calibrated species tree of all Crocodylia and estimate the spatial pattern of diversification within Crocodylus. For the first time, a fully resolved phylogenetic estimate of all Crocodylia is well-supported. The results overturn traditional views of the evolution of Crocodylus by demonstrating that the true crocodiles are not "living-fossils" that originated in Africa. Rather, Crocodylus originated from an ancestor in the tropics of the Late Miocene Indo-Pacific, and rapidly radiated and dispersed around the globe during a period marked by mass extinctions of fellow crocodylians. The findings also reveal more diversity within the genus than is recognized by current taxonomy. 相似文献