Use of historical and contemporary distribution of mammals in China to inform conservation

A systematic understanding of dynamic animal extinction trajectories for different regions in a nation like China is critically important to developing practical conservation strategies. We explored historical and contemporary changes in terrestrial mammalian diversity to determine how diversity in each of the 5 regions in China has changed over time and to examine the conservation potential of these regions. We used records from databases on Pleistocene mammalian fossils and historical distribution records (1175–2020) for Primates (as a case study) to reconstruct evolutionary and historical distribution trajectories of the 11 orders of terrestrial mammals and to predict their prospective survival based on the national conservation strategy applied. The results indicated that since the Pleistocene, 4–5 mammalian orders have been lost in the northeast, 3 in central China, 2 along the coast, and 1 in the northwest. In the southwest, all 11 orders were maintained. Contemporarily, the coast and southwest had the highest and second-highest species densities. The southwest region and southeastern sections of the northwest region were the most historically and contemporarily diverse areas, which suggests that they should be the first priority for protected area (PA) designation. The central and coastal areas should be secondarily prioritized. In these 2 regions, conservation should focus on human coexistence with nature. Less attention should be paid to the PA in the northeast and western northwest because in these areas ecosystems are depauperate and the climate is harsh. Conservation in these areas should focus principally on avoiding further human encroachment on natural areas. Article impact statement: Historical and contemporary patterns of extinction can be a basis for mammalian conservation strategies.     

Overview and recent developments in cell-based noninvasive prenatal testing

Investigators have long been interested in the natural phenomenon of fetal and placental cell trafficking into the maternal circulation. The scarcity of these circulating cells makes their detection and isolation technically challenging. However, as a DNA source of fetal origin not mixed with maternal DNA, they have the potential of considerable benefit over circulating cell-free DNA-based noninvasive prenatal genetic testing (NIPT). Endocervical trophoblasts, which are less rare but more challenging to recover are also being investigated as an approach for cell-based NIPT. We review published studies from around the world describing both forms of cell-based NIPT and highlight the different approaches’ advantages and drawbacks. We also offer guidance for developing a sound cell-based NIPT protocol.     

Environmental hypoxia and haemocyanin between-individual variability in Norway lobsters Nephrops norvegicus (L.)

The extent to which exposure to environmental hypoxia (PO₂=8, 6, and 4 kPa, approximately 40%, 30%, and 20% saturation, respectively) resulted in an increase in the concentration of the respiratory pigment haemocyanin ([Hc]) in individuals of the Norway lobster Nephrops norvegicus depended crucially on the initial [Hc] as well as the intensity of the hypoxia itself. While mean [Hc] did increase with decreasing PO₂ (and the variation decreased), for individuals with relatively high initial [Hc] there was no change or even a decrease observed. The greatest hypoxia-related increases in [Hc] were observed in the individuals with the lowest initial [Hc]. Consequently the notion of an 'optimum' [Hc] for a given level of oxygenation was postulated. The changes in [Hc] recorded took place over a considerably shorter time scale (hours rather than days) than has been observed in previous studies. It was not possible to correlate environmental PO₂ and median [Hc] in the field. However, it was interesting that the [Hc] frequency distribution curve for lobsters collected from a site that had been markedly hypoxic (PO₂=8.0 kPa, approximately 40% saturation) until a few days before sampling was almost exactly the same shape (i.e. leptokurtic) and position (i.e. similar median) to that obtained when lobsters were exposed to PO₂=8.0 kPa in the laboratory. Although it would have been desirable to investigate the effect of hypoxia on the frequency distribution of a physiological trait, in this case [Hc], it was not possible due to insufficient sample size, even though the sample sizes employed were considerably larger than those normally used in physiological investigations.     

Flexible reproductive strategies in tropical and temperate Sepioteuthis squids

A major difficulty confronting the determination of cephalopod reproductive life history is assessing over what portion of the life span an individual is reproductively mature and actively depositing eggs. This paper assesses the potential of the tropical Sepioteuthis lessoniana and two genetic types of the temperate Sepioteuthis australis, to spawn multiple batches of eggs at discrete times throughout the adult life span. This is achieved by histological examination of the ovarian gametogenic cycle and detailed morphological assessments of the reproductive system, in conjunction with other biological information. The genetic type of S. australis found at the northern limits of its Australian distribution showed evidence of a high correlation between body size and quantity of mature eggs, suggesting that eggs may be accumulating to be laid in a single batch. Although maturation was also a size-related process in S. lessoniana and Tasmanian S. australis, oviduct size was not correlated with body weight in mature females, which is indicative of multiple spawning. Further supporting evidence includes relatively low gonadosomatic indices, the heavier weight of the ovary relative to the oviduct, and the feeding activity of mature animals. Mature S. lessoniana and S. australis individuals were present at each location over very wide age and size ranges. In Tasmanian waters, there were distinct seasonal differences in the reproductive biology of S. australis. Summer-caught individuals had much higher gonadosomatic indices and may have been laying larger batches of eggs compared with winter-caught individuals. Summer-caught females also showed a negative correlation between egg size and egg number within the oviduct, suggesting that some individuals were producing fewer, larger eggs and others many smaller eggs. Evidence suggests that considerable flexibility is inherent in the reproductive strategy of both S. lessoniana and S. australis. Received: 11 May 2000 / Accepted: 12 September 2000