The Effect of Temperature on Reproductive Characteristics of an Asexually Reproducing Rotifer (Class Bdelloidea)

Most organisms exhibit sexual reproduction. Rotifers of the class Bdelloidea, however, seem to be a notable exception to this pattern. No male bdelloid individuals have ever been observed, and females apparently reproduce entirely through parthenogenesis. Sexual reproduction occurs in rotifers of the class Monogononta, and in many cases it is induced by environmental cues (e.g. temperature, diet). In this study, Philodina sp. was examined to determine if variations in temperature could induce a sexual cycle in bdelloid rotifers. Sibling individuals (clones) were raised with equal amounts of food at 20°C and 30°C. Newly hatched offspring produced by these individuals were counted and removed at approximately 12 hour intervals until the parent died. Individuals exhibiting unusual characteristics were isolated as possible males and raised for closer examination. No males were positively identified. However, temperature greatly affected reproduction rates. At 30°C individuals had a significantly greater rate of reproductive (Q10 = 2.34) and produced more offspring than those at 20°C. Furthermore, age at the start of reproduction was significantly earlier at 30°C than at 20°C. Unexpectedly, presumed genetically identical clones of Philodina sp. showed significant variation in lifespan when raised in equivalent environmental conditions

Return to Beringia: Parasites Reveal Cryptic Biogeographic History of North American Pikas

Traditional concepts of the Bering Land Bridge as a zone of predominantly eastward expansion from Eurasia and a staging area for subsequent colonization of lower latitudes in North America led to early inferences regarding biogeographic histories of North American faunas, many of which remain untested. Here we apply a host–parasite comparative phylogeographical (HPCP) approach to evaluate one such history, by testing competing biogeographic hypotheses for five lineages of host-specific parasites shared by the collared pika (Ochotona collaris) and American pika (Ochotona princeps) of North America. We determine whether the southern host species (O. princeps) was descended from a northern ancestor or vice versa. Three parasite phylogenies revealed patterns consistent with the hypothesis of a southern origin, which is corroborated by four additional parasite lineages restricted to O. princeps. This finding reverses the traditional narrative for the origins of North American pikas and highlights the role of dispersal from temperate North America into Beringia in structuring northern diversity considerably prior to the Holocene. By evaluating multiple parasite lineages simultaneously, the study demonstrates the power of HPCP for resolving complex biogeographic histories that are not revealed by characteristics of the host alone

Climate\u27s Role in Polar Bear Past [Letters]

Striking temporal concordance between the new date for divergence of polar bears and persistent freezing of the Arctic Ocean suggests that this may be one of relatively few instances in which a specific paleoclimatological episode can be convincingly linked to a specific evolutionary event, and it provides vivid demonstration of climatic forcing as a determinant of diversification in biological systems

Resolving the Evolutionary History of Campanula (Campanulaceae) in Western North America

Recent phylogenetic works have begun to address long-standing questions regarding the systematics of Campanula (Campanulaceae). Yet, aspects of the evolutionary history, particularly in northwestern North America, remain unresolved. Thus, our primary goal in this study was to infer the phylogenetic positions of northwestern Campanula species within the greater Campanuloideae tree. We combined new sequence data from 5 markers (atpB, rbcL, matK, and trnL-F regions of the chloroplast and the nuclear ITS) representing 12 species of Campanula with previously published datasets for worldwide campanuloids, allowing us to include approximately 75% of North American Campanuleae in a phylogenetic analysis of the Campanuloideae. Because all but one of North American Campanula species are nested within a single campanuloid subclade (the Rapunculus clade), we conducted a separate set of analyses focused specifically on this group. Our findings show that i) the campanuloids have colonized North America at least 6 times, 4 of which led to radiations, ii) all but one North American campanuloid are nested within the Rapunculus clade, iii) in northwestern North America, a C. piperi – C. lasiocarpa ancestor gave rise to a monophyletic Cordilleran clade that is sister to a clade containing C. rotundifolia, iv) within the Cordilleran clade, C. parryi var. parryi and C. parryi var. idahoensis exhibit a deep, species-level genetic divergence, and v) C. rotundifolia is genetically diverse across its range and polyphyletic. Potential causes of diversification and endemism in northwestern North America are discussed

Discovery of New \u3ci\u3eOhbayashinema\u3c/i\u3e spp. (Nematoda: Heligmosomoidea) in \u3ci\u3eOchotona princeps\u3c/i\u3e and \u3ci\u3eOchotona cansus\u3c/i\u3e (Lagomorpha: Ochotonidae) from Western North America and Central Asia, with Considerations of Historical Biogeography

Three new species of Ohbayashinema (Nematoda, Heligmosomoidea) are described from localities in western North America and central Asia. Two of these species, Ohbayashinema nearctica n. sp. and Ohbayashinema aspeira n. sp., are parasitic in American pika, Ochotona princeps. Ohbayashinema nearctica is differentiated from the 5 known species of the genus parasitic in Ochotonidae from the Old World by very long spicules and an oblique axis of orientation for the ridges composing the synlophe. Ohbayashinema aspeira, described only from females, is similar to Oh. nearctica based on the number of cuticular ridges at the midbody. It is mainly differentiated by an uncoiled anterior extremity and by near equal dimensions of the vestibule and the uterus. The third species, Ohbayashinema patriciae n. sp., is parasitic in Gansu pika, Ochotona cansus, from China. It is similar to Ohbayashinema erbaevae parasitic in Ochotona dauurica from Buriatia and Ohbayashinema ochotoni in Ochotona macrotis from Nepal, based on the length of the spicules and the ratio of spicule length to body length. It differs from the former species by possessing a smaller number of cuticular ridges and in the comparative length of the vestibule and infundibulum. Related to Oh. ochotoni by an identical number of cuticular ridges at the mid-body, it differs from this species in having smaller ridges in the dorsal rather than ventral field and in the dimensions of the dorsal ray where rays 9 are less than rays 10. Species of Ohbayashinema appear to be host-specific among the Ochotonidae but had not been previously reported in pikas from the Nearctic. Although much remains to be demonstrated about the diversity for helminths in pikas, it is apparent that factors associated with the assembly and structure of parasite faunas have been complex, involving episodic processes for geographic and host colonization along with coevolutionary mechanisms. Understanding the historical factors, particularly climate-driven fluctuations in geographic range, that have structured these faunas suggests that the current regime for global warming and habitat modification has considerable implications for the continuity of already localized assemblages of hosts and parasites

\u3ci\u3eHymenolepis folkertsi\u3c/i\u3e n. sp. (Eucestoda: Hymenolepididae) in the Oldfield Mouse \u3ci\u3ePeromyscus polionotus\u3c/i\u3e (Wagner) (Rodentia: Cricetidae: Neotominae) from the Southeastern Nearctic with Comments on Tapeworm Faunal Diversity among Deer Mice

A previously unrecognized species of hymenolepidid cestode attributable to Hymenolepis is described based on specimens in Peromyscus polionotus, oldfield mouse, from Georgia, United States, near the southeastern coast of continental North America. Specimens of Hymenolepis folkertsi n. sp. differ from those attributed to most other species in the genus by having testes arranged in a triangle and a scolex with a prominent rostrum-like protrusion. The newly recognized species is further distinguished by the relative position and length of the cirrus sac, shape of seminal receptacle, and relative size of external seminal vesicle and seminal receptacle. Hymenolepidid cestodes have sporadically been reported among the highly diverse assemblage of Peromyscus which includes fifty-six distinct species in the Nearctic. Although the host genus has a great temporal duration and is endemic to the Nearctic, current evidence suggests that tapeworm faunal diversity reflects relatively recent assembly through bouts of host switching among other cricetid, murid, and geomyid rodents in sympatry

Finding Them before They Find Us: Informatics, Parasites, and Environments in Accelerating Climate Change

Parasites are agents of disease in humans, livestock, crops, and wildlife and are powerful representations of the ecological and historical context of the diseases they cause. Recognizing a nexus of professional opportunities and global public need, we gathered at the Cedar Point Biological Station of the University of Nebraska in September 2012 to formulate a cooperative and broad platform for providing essential information about the evolution, ecology, and epidemiology of parasites across host groups, parasite groups, geographical regions, and ecosystem types. A general protocol, documentation–assessment–monitoring–action (DAMA), suggests an integrated proposal to build a proactive capacity to understand, anticipate, and respond to the outcomes of accelerating environmental change. We seek to catalyze discussion and mobilize action within the parasitological community and, more widely, among zoologists and disease ecologists at a time of expanding environmental perturbation