Harsh Habitats Research Articles

Environmental correlates of the intrinsic rate of natural increase in primates.

The intrinsic rate of natural increase (r m) is calculated for 72 primate species, using Cole's (1954) equation. The value of r m relative to body mass is then calculated by use of allometric analysis. Both r mand relative r m are used to test the prediction that animals in unpredictable and/or harsh habitats will have a higher r mthan will those in more predictable and/or less harsh habitats. No significant link between habitat type and r mis found. However, correlations between ecology and relative r msuggest that relative r mis high in primate species living in more open habitats and low in species found in primary rainforest. Although there are few correlations between relative r m and climate parameters, those that are found suggest that variable climates, dry climates and hot climates will select for a high relative r m.

Avian diversity patterns at a constructed wetland: Use of ecological theory in the evaluation of a mine land reclamation technique

ABSTRACT Birds were surveyed at a constructed cattail (Typha latifolia) wetland near Coshocton, Ohio, during May and June of 1988, 1989 and 1990, as part of an overall assessment of the environmental integrity of a mine reclamation project. Comparison surveys were also completed at three nearby natural wetland sites similar in size and dominant wetland vegetation. The constructed wetland was established in November 1985 to serve as a treatment system for a deep mine discharge. Results demonstrated the constructed wetland exhibited the fewest number of bird feeding guilds per survey and an intermediate level of bird abundance relative to all sites examined. Significant differences in species diversity and feeding guild diversity patterns were not detected among sites; however, the constructed wetland supported a bird community with a significantly lower species evenness index, suggesting a more harsh and variable habitat relative to the natural wetlands. Our data suggest that the availability of adequate n...

Photoperiod, Melatonin Secretion, and Sexual Maturation in a Tropical Rodent1

Descendants of a sample of cane mice (Zygodontomys brevicauda) trapped at 8 degrees latitude in Venezuela were tested for reproductive photoresponsiveness. This species breeds continuously, year around, despite living in a seasonally harsh habitat. At 50 days of age there were no differences in the weights of the testes or seminal vesicles or in sperm counts of males born and reared on 16L:8D, 13L:11D, 11L:13D, or 8L:16D photoperiods, although there were small differences in body weight. Females born and reared on 16L:8D vs. 8L:16D cycles became pregnant at the same rates and ages when paired with males at 21 or 31 days of age. The daily duration of melatonin secretion depended on the length of the dark phase of the cycle in both sexes. Circulating levels of melatonin were elevated for 8 h on a 16L:8D cycle and for between 9 and 16 h on an 8L:16D cycle. In this tropical species, the neuroendocrine pathway that links photoperiod to reproduction apparently is disconnected somewhere between melatonin and gonadotropin secretion, causing cane mice to be reproductively unresponsive to variation in photoperiod.

A New Species of the South American Genus Nassauvia (Compositae: Mutisieae) from Chilean Patagonia

Nassauvia coronipappa Arroyo & Marticorena, from Cerro Donoso in eastern Chilean Patagonia, is described and illustrated. It is distinguished by trifid inner involucral bracts and persistent, brief, laciniate-dentate, crown-like pappus incompletely surrounding summit of the achene. The distinctive pappus may be related to selection, in harsh alpine habitats, against dispersal away from nurse sites.Nassauvia coronipappa belongs to subgenusNassauvia. It is seen as a relict member of an independent line of evolution, whose closest affinities are with sectionNassauvia of that subgenus.

Development of the Lignotuber and Plant Form in Lehmannianae

In lignotuberous species of the Lehmannianae, lignotuber formation is preceded by the appearance of a crescent-shaped array of accessory buds, adaxial to the axillary bud. Lignotubers may be formed at successive nodes but those with only one upper accessory bud (which may be present even in non- lignotuberous species) do not form lignotubers. The subsequent development of the lignotuber is described, as is the development of the seedling. Seedling shoot growth is characterized by indeterminate growth and, like that of the adult shoots, is sympodial. In well protected sites lignotuberous species may develop into small, single-stemmed trees but in harsher habitats death of the seedling shoot and its replacement from lignotuber buds result in enlargement of the lignotuber and enhance the tendency to adopt a mallee (many-stemmed) form. Non-lignotuberous and lignotuberous species of the Lehmannianae occur side-by-side in habitats that are prone to fire. Lignotuberous species survive shoot-destructive vicissitudes, such as fire, by replacement from the lignotuber. Whereas flowering and fruiting of seedlings of lignotuberous species may be postponed for many years, seed production is precocious in the non-lignotuberous species of the series. This is regarded as an alternative adaptation to fire, which is one of the major factors of the habitats of the Lehmannianae. Even-aged pole stands of the non-lignotuberous species result from regeneration from seed, after fire. Following the production of gaps in the canopy and the thinning out of the stand, pole-stage trees assume their mature form by outgrowth of epicormic shoots, including some placed near the base of the trunk.

Re-discovery of Haemoproteus kopki (De Mello, 1916) in two geckoes from the Afghan border of Pakistan

SummaryHaemoproteus kopki (De Mello, 1916) is reported from the geckoes Teratoscincus scincus and T. microlepis collected in three localities on the Afghan border of Pakistan. A detailed description of H. kopki is provided in correlation with the courses of an initial, acute infection and a relapsed, chronic infection. Haemoproteus kopki is characterized by large round or oval gametocytes which show sexual dimorphism in distribution of pigment: macrogametocytes show pigment dispersed in dark granules throughout the cytoplasm, while pigment in microgametocytes is aggregated into large, round golden masses within vacuoles in one, or rarely two foci. Other sexual differences exist in gametocyte dimensions. Gametocytes produced in the relapse infection grew much more slowly than did those of the initial infection, and never attained a comparable size despite being observed for twice the length of time. Despite a maximum parasitaemia of 53·8% in the initial infection, increased erythropoiesis did not occur. No asexual stages were found in tissues examined. The presence of mixed infections of H. kopki, Leishmania sp. and microfilariae in a harsh sand dune habitat with presumably limited dipteran fauna suggests their having a common vector in intimate association with the burrows inhabited by the geckoes.

Oasis saints of Eastern Libya in North African context

The saints of Augila Oasis2 in the east Libyan Sahara Desert play a significant part in this community where a harsh physical environment and the tenacious faith of Islam are dominant themes. Augila's saints are in some ways unlike the most well-known holy men of North Africa, whose sanctity is usually pre-ordained by membership in a holy lineage or through a teacher-disciple relationship (Gellner 1968). Rather, the Oasis holy men, who neither belong to a formal religious lineage or fraternity nor receive special training in the formal religion, are ordinary men who are only sanctified on the termination of their earthly existence.3 One major, ostensible reason for the boost to sainthood of the religiously untutored man4 is his enactment of a miracle judged by his kinsmen particularly and the community generally to be divinely inspired. Such godly-inspired acts are usually considered to be wholly altruistic and therefore tied to the welfare of the community. Another reason for sainthood is the need for the Oasis inhabitants to rally around a set of moral and ethical precepts which periodically reaffirm their beliefs in God, in individual immortality and in their traditional lifeway which has been linked in almost spartan fashion to a harsh habitat of limited resources. This paper describes and defines saints and places them in North African context, with the purpose first of demonstrating their continuity and discontinuity with North African saints generally and secondly of describing the conditions under which the local saints have arisen and are perpetuated. In the first section of the paper there is a presentation of some of the saints I encountered in my fieldwork. Then, a comparison of Oasis holy men with a small sample of North African saints is made.5 The basic distinctions between them are dealt with analytically. In order to highlight the differences, saints from the Oasis are compared with the mountain holy men of Morocco and a Cairo saint. Finally, the rather significant variability among these three types of saints, particularly in the kind and degree of their politicization, is explained by variable ecological, socio-economic, and political forces at work on the societies of their origin.

A methodological problem in genecology. Seeds versus clones as source material for uniform gardens

Plants derived from both achenes and rootstock cuttings (ramets) were used to examine genetically based differences between two populations of Rumex crispus L. from two contrasting habitats, i.e., flood plain and pasture. Offspring from both sources were grown under cultivation in a uniform garden. Fifty-eight characters were determined for each individual. Within the pasture population only, seedling offspring differed significantly from plants obtained from ramets. Characteristics of the two populations were compared using (i) seedling offspring and (ii) ramets. More significant differences were found in the former set of comparisons.In the harsh but predictable flood plain habitat, genetic heterogeneity within the population was less than that found among plants from the pasture. Reasons for this difference are discussed.

Lntertidal Macrophyte Comrnunities from Pacific Baja California and the Upper Gulf of California Relatively Constant vs. Environmentally Fluctuating Systems

The adaptive features of marine macrophyte communities in a markedly fluctuating environment (the northern Gulf of California) were contrasted with those characteristic of a climatically more constant system (the Pacific coast of the Baja Peninsula) in the light of a priori predictions. In general, the data suggest the importance of intermediate disturbance in permitting a mosaic of young to mature community types to CO-occur in accordance with previous theories. In the less-disturbed (more constant) Pacific coast system, the predominant macrophytes were either calcareous algae or structurally complex vascular plants, with early successional species such as Ulva californica and Gelidium pusillum being abundant only on recently overturned boulders. The majority of the overall productivity on the Pacific coast was provided by the larger, most abundant species. However, production rates per unit of thallus were highest for small species with high surface area to volume ratios (i. e., Navicula sp., U. californica. Chondria californica) that grew on the overturned rocks. As a group, the macrophytes that dominated the standing stock had considerably lower net productivity and larger thalli which were geometrically complex and formed a layered community that increased spatial heterogeneity. The Pacific site was more diverse (Shannon-Weaver H') , having higher values for both richness (species numbers) and evenness (J'). Conversely, in the seasonably disturbed sites (due to catastrophic environmental fluctuat~ons) annual or opportunistic forms with high reproductive output (e. g.. U. rigida, various species of Colpomenia, as well as eurytopic blue-green algae that are indicative of harsh habitats) were significantly more abundant (P < 0.05, Mann-Whitney U-test) than at the Pacific site. These populations rapidly recolonized available substrate following periods of mortality caused by extreme heat, desiccation and insolation during summer low tides. The smaller turf-like growth habits of the dominant macrophytes in the Gulf communities provided little spatial heterogeneity and this appeared to further limit macrobiotic diversity. Forms that contained considerable structural tissue or calcium carbonate as part of their thallus weight were the lowest producers at the Gulf sites and were of moderate to low abundance. Selection in the seasonally disturbed environments appears to have favored a predominance of structurally simple, opportunistic species (e. g., Ulva, Colpomenia) having high individual net productivity. In the less disturbed Pacific system, photosynthetic rates of the large predominant species (e. g., calcareous forms, thick forms, prostrate crusts, morphologically differentiated flowering plants) were lower because they have evolved structurally complex thalli (at the expense of photosynthetic tissue) in order to withstand the greater pressures of biological interactions. Most of the populational and community features at the Pacific site suggest a relatively longlived, mature intertidal system containing a mosaic of younger successional stages; whereas, environmental fluctuations beyond the homeostatic capabilities of most marine plants maintain the upper Gulf macrophyte communities in a simpler subclimax condition.