Conceptual Issues and Methodology in Kin-recognition Research: A Critical Discussion

We operationally define kin-recognition and discuss methodological and conceptual issues that arise in its study, citing examples from the literature that illustrate particular points. We define and examine three components of kin-recognition (expression, perception, and action), and discuss why some experimental designs fail to distinguish among the components. We also point out ways that experimental designs might be modified to unlink the components. We discuss three general issues central to assays of kin-recognition: the functional significance of assays, multiple- and single-behavior assays, and potential biases in assays. The potential biases we consider are nonblind behavioral assays and the pooling of dependent data. We also examine negative results and, in particular, those factors that can produce negative results when recognition ability is present. Finally, we discuss kin-recognition in natural contexts, emphasizing the potential dangers of uncritically extrapolating the results of laboratory studies to field contexts.     

Territorial status and survival in red grouse Lagopus lagopus scoticus: hope for the doomed surplus?

A previous study of survival in territorial and non-territorial red grouse Lagopus lagopus scoticus conducted between 1957 and 1967 found that territorial status in the autumn pre-determined over-winter survival. A very high proportion of territorial birds survived and virtually all non-territorial birds died or emigrated. We tested the hypothesis that over-winter survival was dependent on territorial status within four grouse populations in Scotland between 1986 and 1993. In contrast to the previous study, 66% of non-territorial birds survived over winter compared to approximately 70% of territorial birds. There was no significant effect of territorial status on the survival estimates. Moreover, some of the birds considered to be non-territorial during autumn went on to successfully raise a brood. We suggest that on our study sites, territory ownership in autumn did not greatly influence over-winter survival, and territorial behaviour did not determine breeding density as previously supposed. We postulate differences with other studies may reflect variations in scale and predation pressure.     

ECOTYPIC DIVERGENCE IN ALPINE POLEMONIUM VISCOSUM: GENETIC STRUCTURE,QUANTITATIVE VARIATION,AND LOCAL ADAPTATION

Polemonium viscosum has a continuous distribution from 3,500 m in the krummholz to 4,025 m on the summit ridges of Pennsylvania Mountain, Colorado. Seeds produced by plants at opposite ends of this cline, 1.5 km apart, differed significantly at allozyme loci in two consecutive breeding seasons. Mean multilocus F_st values for both years (0.015 and 0.069) were significantly different from zero, indicating restricted gene exchange between subpopulations. Average allele frequencies at two individual loci also differed significantly between families comprising krummholz and summit subpopulations. Progeny of plants growing on the summit had higher leaf production rates, more densely packed leaflets, and lower resistance to aphids than progeny of plants growing in the krummholz site, when tested under greenhouse conditions. These differences probably reflect the restricted opportunities for growth and severe exposure at high elevations, and the increased risk from herbivores near timberline. The two subpopulations did not differ in leaf length (stature), leaf width, or pubescence. Reciprocal transplanting of seedlings between krummholz and summit sites confirmed that the differences were adaptive, since progeny from each subpopulation performed significantly better in their parent's habitat. Coordinated studies of genetic structure, quantitative variation, and local adaptation across the elevational range of P. viscosum provide a comprehensive view of ecotypic divergence in this widespread alpine plant.     

Olive: a key gene required for chlorophyll biosynthesis in Antirrhinum majus.

Olive (oli) is a recessive nuclear mutation of Antirrhinum majus which reduces the level of chlorophyll pigmentation and affects the ultrastructure of chloroplasts. The oli-605 allele carries a Tam3 transposon insertion which has allowed the locus to be isolated. The oli gene encodes a large putative protein of 153 kDa which shows homology to the products of two bacterial genes necessary for tetrapyrrole-metal chelation during the synthesis of bacteriochlorophyll or cobyrinic acid. We therefore propose that the product of the oli gene is necessary for a key step of chlorophyll synthesis: the chelation of magnesium by protoporphyrin IX. Somatic reversion of the oli-605 allele produces chimeric plants which indicate that the oli gene functions cell-autonomously. Expression of oli is restricted to photosynthetic cells and repressed by light, suggesting that it may be involved in regulating the rate of chlorophyll synthesis in green tissues.     

Evaluation of freezing injury and freeze-thaw injury to membranes of Saskatoon serviceberry twigs by measuring HCN release

The influence of thawing on freeze-injured Saskatoon serviceberry ( Amelanchier alnifolia Nutt.) twigs was evaluated by refreezing freeze-thawed twigs and comparing the HCN release at -5°C fro these twigs to the HCN release at -5°C from twigs that had not been thawed. An effect of thawing depended on the physiological state of the twigs, on the degree of freezing stress, or on both. Manifestation of membrane injury does not have an absolute dependence on thawing. Post-thaw temperature influences manifestation of injury, since twigs warmed to 30°C released more HCN than twigs warmed to 1°C when refrozen to -5°C. Although thawing and post-thaw conditions can influence the magnitude of membrane injury, the critical event leading to injury occurs while plants are frozen.     

Histopathology of virus-like particles in Heliothis spp

Larvae of Heliothis spp. collected from cotton, soybean, and peanut fields in South Carolina were found to be infected with virus-like particles (VLPs). Infected larvae became pale and swollen, stopped feeding, and remained alive for 2–3 weeks. Hemolymph from these larvae was milky and contained numerous spherical bodies ranging in diameter from 2 to 10 μm. The hemolymph also contained VLPs which were oval and measured 375 × 125 nm. Infectivity tests with crude saline extracts of infected larvae demonstrated that the pathogen could be transmitted by injection but not per os. The spherical bodies contained VLPs (387 × 149 nm) surrounded by two envelopes and packed together in clusters. These VLPs were also found in fat body cells, cuticular epithelial cells, tracheal cells, and connective tissue associated with the body wall and the gut. They were not found in muscle tissue or in midgut epithelial cells. Similar VLPs have been found in Heliothis zea from Mississippi and Trichoplusia ni from California, but a positive identification of the VLPs has not been made in any of these studies. Morphologically they appear to be distinct from any other previously described insect viruses.     

The cellulase activity of an extreme thermophile

Summary The carboxymethylcellulase activity concentrated from the extremely thermophilic anaerobe H173 was found to have a pH optimum of 6.5–7.0. The enzyme activity was stabilised by the addition of dithiothreitol and CaCl₂·2H₂O and was very stable at 80° C, retaining 77% of the initial activity after 120 min incubtation. At min and after 120 min only 3% of the initial activity remained. With the enzyme dissolved in buffer, glucose and cellobiose were formed from the hydrolosis of Avicel. In culture medium the Avicel-solubilising activity was insensitive to the presence of up tp 50 mm glucose and showed linear glucose accumulation over a period of days at 70° C. HPLC analysis established that glucose was the major end-product of hydrolysis in the culture broths.Offprint requests to: H. W. Morgan     

Factors affecting the survival of bisected sheep embryos in vivo

Two experiments were carried out to examine the effects of different factors on the survival of split sheep embryos. In Experiment 1, embryos collected on Day-6, Day-7 or Day-8 were bisected and transferred into recipient ewes in pairs. The proportions of Day-6, Day-7 and Day-8 demi-embryos developing to lambs were 26% (14 54 ), 30% (31 102 ) and 32% (24 74 ), respectively. Replacement of bisected late morula to expanded late blastocyst stage embryos into zonae did not affect their survival rate (P>0.5). The proportion of demi-embryos developing to lambs in recipients with two or more ovulations was higher (35%, 53 152 ) than in recipients with a single ovulation (21%, 16 78 ; P<0.05). In Experiment 2, Day-6 embryos were split with or without exposure to 0.25 M of sucrose and were transferred into recipients in pairs or singly. Exposure to 0.25 M of sucrose decreased the proportion of split embryos developing to lambs compared with that of the controls (31%, 22 70 vs 49%, 34 70 ; P<0.05). The effects of the number of demi-embryos transferred or the stage of development on the survival rate were not significant (P>0.05). The number of lambs born per original embryo was the highest when the embryos were split without exposure to sucrose and transferred into recipients singly (106%, 17 16 ).     

Nutrition ofPinus caribaea in its native savanna habitat

Summary Fertility levels in soils beneathPinus caribaea trees were examined in the Mountain Pine Ridge savannas, Belize, where fire control has precipitated the development of pine woodland. Slight surface soil enrichment was recorded beneath pine canopies, but to levels well below those found beneath associated hardwoods. Estimates of total nutrient pools beneath trees showed modest cation accumulation beneath a 73 year old tree but some defecits in Ca and Mg beneath a 24 year old tree. A tap root cutting experiment on trees of the same species revealed no significant declines in foliar nutrient levels after 19 months. It is concluded that no pronounced long-term deterioration in soil fertility levels is developing beneath stands ofP. caribaea in the savanna, although some temporary nutrient declines may exist beneath young pine stands. Atmospheric inputs are the most likely source of nutrient accretion and it is suggested that the establishment of hardwood associates with pine may enhance the rates of nutrient capture from this source.     

Mate selection by female katydids (Orthoptera: Tettigoniidae, Conocephalus nigropleurum)

Female katydids receive a large spermatophore at mating which they subsequently eat. Available evidence indicates that spermatophore nutrients are important to female reproduction. Heavier males produce larger spermatophores. When given the choice between two singing males of different weights, females always mated with the larger individual.