ABSTRACT
Females' perspectives like males' perspectives are used to generate hypotheses or draw conclusions about the evolution of social behavior. These gendered perspectives probably originate from the empathetic responses of researchers to the ecological problems faced by the individuals they study. Females' perspectives thus stare with the main ecological problems that females of ''typical species'' (read as: ''species like us'') have to solve just as males' perspectives start with empathetic responses to the problems that males of ''typical species'' have to solve. Because men have predominated in the field of avian behavioral ecology, females' perspectives are yet to be as clearly articulated or frequently investigated as males' perspectives. Happily, this asymmetry in our ranks is changing, so that more attention to our questions from females' perspectives is accruing. Here I discuss 10 principles of females' perspectives that are particularly obvious to me. These were too-long-overlooked or previously ignored facts that contrast with predominating myths about females. These mythic notions seem to result from thinking about females from males' perspectives only rather than from more inclusive ones. I am not claiming that my list is a comprehensive one, nor that my view of females' perspectives is the only view. I am not claiming that females' perspectives can only be articulated and investigated by women, only that it is more likely that women will. Pull incorporation of females' perspectives into avian behavioral ecology will be a result of inclusive theories. And, of course, inclusive theories can and should be cast and investigated by men as web as women. I contributed to this forum in the hopes of generating discussions that will. facilitate inclusion of questions about females in studies of the evolution of social behavior. From this I expect increased understanding of the details of sexual dialectics. I look forward to the time when we can predict the traits the pendulum swing will bring: what are females' solutions to the ecological (selectively significant) problems created for them by males and what are males' solutions to the ecological problems created for them by females. Despite my obvious focus on the selective forces created by the interactions between the sexes, I suspect that the full nature of social behavior that we seek to discover will only come when we have theories that account for variation among individuals - beyond sex, beyond gender.

ABSTRACT
If behavioral isolation between species can evolve as a consequence of sexual selection within a species, then traits that are both sexually selected and used as a criterion of species recognition by females should be identifiable. The broad male head of the Hawaiian picture-winged fly Drosophila heteroneura is a novel sexual dimorphism that may be sexually selected and involved in behavioral isolation from D. silvestris. We found that males with broad heads are more successful in sexual selection, both through female mate choice and through aggressive interactions. However, female D. heteroneura do not discriminate against hybrids on the basis of their head width. Thus, this novel trait is sexually selected but is not a major contributor to species recognition. Our methods should be applicable to other species in which behavioral isolation is a factor. |FULL TEXT|

ABSTRACT
We present a new simple model for the evolution of premating reproductive isolation. Using this model we first analyze the level of genetic variability maintained by mutation in a large stable population. Then we consider the plausibility of the evolution of strong premating reproductive isolation after a founder event. We demonstrate that after a founder event a new adaptive combination of genes may rise to high frequencies in the presence of an old combination of genes. We compare the probabilities of speciation after a founder event with those in a stable population and with those when reproductive isolation is due to viability selection against hybrids. We argue that premating reproductive isolation is more efficient than postmating reproductive isolation in maintaining the integrity of sympatric species. This might have contributed to the pattern of stronger premating isolation than postmating isolation between closely related pairs of sympatric species.

ABSTRACT
Quantitative genetic models have indicated that sexual selection may lead to speciation in isolated populations or to exaggeration of differences in male traits along a dine. We argue that where female mate preference and opposing natural selection against conspicuous males have produced a stable equilibrium in male trait genotype, a reversed female mate preference may invade the population, initially assisted by reduced male mortality. The consequent linkage disequilibrium may lead to rapid sympatric speciation. Assuming a four-locus quantitative male trait and single-locus female preference rule and overlapping generations, we present a simulation model which indicates that reversal of female mate preference in a single individual can lead rapidly to full reproductive isolation in a small population. Speciation may be produced by the proposed mechanism in allopatry, parapatry or full sympatry. We suggest that differences in mating system and its genetic bases may account for some of the differences in speciation rates among lineages.

ABSTRACT
Among fruit-fly species of the genus Drosophila there is remarkable variation in sperm length, with some species producing gigantic sperm (e.g., > 10 times total male body length), These flies are also unusual in that males of some species exhibit a prolonged adult nonreproductive phase, We document sperm length, body size, and sex-specific ages of reproductive maturity for 42 species of Drosophila and, after controlling for phylogeny, test hypotheses to explain the variation in rates of sexual maturation, Results suggest that delayed male maturity is a cost of producing long sperm. A possible physiological mechanism to explain the observed relationship is discussed.  |FULL TEXT|

ABSTRACT
1. Nitrogen (N) and phosphorus (P) availabilities are important ecological determinants of resource use in nature, Despite the wide range of hosts used by species of the genus Drosophila, elemental composition of natural resources of these flies has never been investigated.
2. Total body N and P contents were determined in seven species of wild-caught Drosophila, their natural hosts, and artificial diets routinely used to rear these flies in the laboratory. The flies tested included D. hydei, D, arizonae, D. simulans and D. pseudoobscura collected from rotting fruit (melons), and the cactophilic D. nigrospiracula, D. mojavensis and D. pachea collected from their specific host plants, Saguaro, Organpipe and Senita cactus, respectively.
3. Natural hosts varied in elemental composition, with fruit showing higher N (2.8-4.3% dry mass) and P (0.50-0.67%) levels compared with cacti (0.5-1.6% N; 0.01-0.29% P). No consistent differences in N and P levels were found between healthy and necrotic cactus tissue.
4. Total body N and P also varied among Drosophila species. This variation mirrored the levels of N and P found in the respective hosts and laboratory diets. N:P ratios were consistently lower in female flies compared with conspecific males suggesting phosphorus demands during oogenesis are high.
5. Potential mechanisms by which Drosophila deal with N or P limitation in nature are discussed.

ABSTRACT
The concept of gametic isolation has its origins in 1937 edition of T. Dobzhansky's Genetics and the Origin of Species. Involving either positive assortative fertilization (as opposed to self-incompatibility) or negative assortative fertilization, it occurs after mating but prior to fertilization. Gametic isolation is generally subsumed under either prezygotic or postmating isolation and thus has not been the subject of extensive investigation. Examples of assortative fertilization in Drosophila are reviewed and compared with those of other organisms. Potential mechanisms leading to assortative fertilization are discussed, as are their evolutionary implications.  |FULL TEXT|

ABSTRACT
Forests exhibit much variation in light environments, and this can affect communication among animals, communication between animals and plants, photosynthesis, and plant morphogenesis. Light environments are caused by, and can be predicted from, the geometry of the light paths, the weather conditions, and the time of day. The structure of forests leads to four major light habitats when the sun is not blocked by clouds: forest shade, woodland shade, small gaps, and large gaps. These are characterized by yellow-green, blue-gray, reddish, and ''white'' ambient light spectra, respectively. When the sun is blocked by clouds, the spectra of these four habitats converge on that of large gaps and open areas, so the single light environment during cloudy weather will be called open/cloudy. An additional light environment (early/late) is associated with low sun angles (near dawn or dusk); it is purplish. Each light environment is well defined and was found in forests of Trinidad, Panama, Costa Pica, Australia, California, and Florida. Scattered literature references suggest similar patterns elsewhere in North America, Europe, and Java. Perceived colors of animals, flowers, and fruits depend upon the interaction between ambient light color and the reflectance color of the animal or plant parts. As a result, an animal or plant may have a different appearance in each environment, i.e., a color pattern may be relatively cryptic in some light environments while relatively conspicuous in others. This has strong implications for the joint evolution of visual signals and vision, as well as microhabitat choice. Plant growth and form may also be affected by variation in the color of forest light.

ABSTRACT
Color patterns of natural populations of guppies (Poecilia reticulata) are a compromise between sexual selection and predation avoidance. Field data on ambient light spectra, water transmission spectra, courtship and attack distances, and cone pigments of guppies and their predators were used to calculate measures of conspicuousness of guppies under various combinations of visual conditions and vision. The results suggest that color patterns are relatively more conspicuous to guppies at the times and places of courtship and relatively less conspicuous at the times and places of maximum predator risk. Some implications to the evolution of vision, visual communication and behavior are discussed.

ABSTRACT
There is a bewildering diversity of signals, sensory systems, and signaling behavior. A consideration of how these traits affect each other's evolution explains some of this diversity. Natural selection favors signals, receptors, and signaling behavior that maximize the received signals relative to background noise and minimize signal degradation. Properties of sensory systems bias the direction of evolution of the signals that they receive. For example, females may prefer males whose signals they can perceive more easily, and this will lead to the spread of more easily perceived male traits. Environmental conditions during signal transmission and detection also affect signal perception. Specific environmental conditions will bias the evolutionary direction of behavior, which affects the time and place of signaling as well as microhabitat preferences. Increased specialization of microhabitats and signaling behavior may lead to biased evolution of the sensory systems to work more efficiently. Thus, sensory systems, signals, signaling behavior, and habitat choice are evolutionarily coupled. These suites of traits should coevolve in predictable directions, determined by environmental biophysics, neurobiology, and the genetics of the suites of traits-hence the term "sensory drive." Because conditions vary in space and time, diversity will be generated.

ABSTRACT
Animal communication systems have evolved so that individuals can make decisions based upon the behaviour, physiology or morphology of others. Receiving mechanisms probably evolve to increase the efficiency and reliability of information reception whereas signals probably evolve to increase the efficiency of communication and reliability of manipulation of the receiving individual to the benefit of the emitter. The minimum requirement for clear reception suggests that any study of the evolution and design of communication systems must consider the factors that affect the quality of the received and processed signal. Critical information is needed about how the signal is generated and emitted, how it fares during transmission through air, water or substrate, how it is received and processed by the receiver's sensory and cognitive systems, and the factors which affect the fitness consequences of alternative ways of reacting to the information contained in the signal. These should allow predictions about the kinds and forms of signals used by animals signalling under known conditions. Phylogenetic history, and the geological time a clade spends in different signalling environments, will also affect signal evolution, and hence the success of predictions about signal design. We need to use methods of many different biological fields to understand the design and evolution of signals and signalling systems.

ABSTRACT
Forests exhibit a mosaic of different spectral environments that arise from forest geometry and weather. If visual signals are used in mate choice, then forest geometry and weather will affect reproductive behavior because the appearance of a visual signal depends on the joint effects of ambient light and the animal's reflectance spectra. We investigated three lekking birds at Nourages field station, French Guiana: Rupicola rupicola, Corapipo gutturalis, and Lepidothrix serena. Conspicuousness is a function of ambient light spectra during displays and the reflectance spectra of color pattern elements of the birds and their visual backgrounds. Each species places its lek and performs its lek displays in only one or two of the available light environments, and some may specialize in the more extreme spectra even within each light environment. The color patterns and behavior of each species maximize its visual contrast during its display and reduce it off the lek or on the lek but not displaying. Each species does this with a different combination of colors and light environments. If this phenomenon is general, then it has important implications for the evolution of color patterns and display behavior.

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