Plumage Pattern Research Articles

Differential Development of Sex-related Characters of Chickens from the GSP and PNP/DO Inbred Lines after Left Ovariectomy

To elucidate strain differences in the sex reversal of genetic females to phenotypic males, GSP and PNP/DO females were left ovariectomized (ovx) between one to three days after hatching, and the degree of masculinization based on sex-related characters, histological analysis of the right gonad and hormone assay were assessed at one year of age. The GSP and PNP/DO inbred lines were both derived from the Fayoumi breed and are only differentiated based on the red blood cell antigen type carried by each inbred line. Combs and wattles were found to be significantly bigger (P<0.05) in the GSP ovx compared with the PNP/DO ovx chickens, although male plumage patterns were more pronounced in the PNP/DO ovx. Spurs were observed both in the GSP and PNP/DO ovx chickens with no significant difference (P>0.05) in length compared with the respective male controls, and body weight was not significantly different (P>0.05) compared with the female controls. The weight of the right gonad was significantly heavier (P<0.05) in the GSP ovx than in the PNP/DO ovx. Positive correlations were found in the sex-related characters as well as the plasma testosterone level and right gonad weight in both the GSP and PNP/DO ovx chickens, but not in the spur length, which showed a negative correlation in the PNP/DO ovx chickens. Histological analysis revealed that the right gonads of the PNP/DO ovx chickens were morphologically developed compared with the GSP ovx chickens, which showed more advance stages of spermatogenesis. It could be inferred that PNP/DO females that exhibit a hereditary persistent right oviduct are more responsive to the masculinizing effect of ovariectomy compared with GSP females, suggesting that genetic background may have a possible contribution to the degree of masculinization and subsequent development of sex related characters.

Influence of weight grouping on the short term egg production of two strains of layer type chicken

An experiment was conducted using 400 pullets each of H and N brown Nick (Strain I) and Black Olympia (Strain 2) to determine the influence of weight grouping on short term egg production traits. The two strains of layer type chickens were separated on the basis of plumage pattern and body weight at three weeks of age. The result indicates that the high bodyweight (HBW) groups were signiicantly (P 0.05) difference betweenthe HBW and LBW lines in strain I for weight o first egg, egg weight at 30 and 40 weeks respectively. Henday rate of lay and total egg mass did not vary according tobodyweightgroups inboth strains 1 and 2 However, the light brown pullet groups (LBHBW and LBLBW) in strain I weresignificantly (P 0.05) difference between the HBW and LBW groups in feed per dozen eggs. The comparative performance between the two strains of chicken showed that strain I was signficanty(P < 0.01) superior to strain 2 in weight of first egg, egg weightat 30 and 40 weeks and henday rate of lay respectively. The two strains of chicken were similar in body weight at first egg and feed per dozen eggs. Based on these results, the only apparent advantage of rearing the HBW and LBW pullet groups separately was in the efficiency of converting feed to eggs in srain I and in weight of first eggs, egg weight at 30 and 40 weeks instrain 2 Between thetwo strains of chicken, farmers may opt for srain I pullets because of its superior performance in egg number and egg weight traits. Keywords: Bodyweight groups, Egg production, Bird strains, Superiority

Taxonomy of the Loggerhead Kingbird (Tyrannus caudifasciatus) Complex (Aves: Tyrannidae)

Abstract We examined the complex of populations of the Loggerhead Kingbird (Tyrannus caudifasciatus), a West Indian endemic. We separate populations in Puerto Rico and Isla Vieques (T. taylori), and Hispaniola (T. gabbii) as distinct species. Subspecific distinction is assigned to populations in Cuba, Isla de Pinos, and Cuban satellites (T. caudifasciatus caudifasciatus); Cayman Islands (T. c. caymanensis); Jamaica (T. c. jamaicensis); and the Bahamas (T. c. bahamensis) on the basis of differences in plumage coloration and pattern, size, vocalizations, and distribution.

Foraging and Plumage Coloration of the Galapagos Lava Heron (Butorides Striata Sundevalli)

The Lava Heron (Butorides striata sundevalli) is a distinctively dark-plumaged heron that feeds along the rocky intertidal shoreline of the Galapagos Islands. The open shoreline used by the Lava Heron differs markedly from the dense swamps used by most populations of Butorides. Larva Herons feed by standing and by walking slowly at the water's edge, averaging only three steps per minute and catching primarily fish, crabs and prawns. Lava Heron foraging is characterized not only by its use of open shoreline, but by an extreme dependence on standing feeding behavior, frequent shifting of feeding sites following the tidal flux across a broad intertidal zone, and importance of crabs in the diet; but overall its foraging does not differ significantly from that used by Butorides elsewhere. The fundamental Butorides foraging strategy appears to have accommodated the habitat shift from dense bushes to open shoreline. Individuals maintain separate feeding territories, with the nest being placed within the territory of one of the pair. Feeding success was 0.12 prey per minute. In that nesting production is low contrasted with other populations, it appears that food may overall be limiting. The Galapagos population differs from South American Striated Herons (Butorides striata striata) in having a longer and stouter bill, a feature that correlates with the importance of crabs in the diet. Although known for its distinctive dark color, plumage ranges from all black to light grey, similar to South American birds. The dark color has been assumed to provide camouflage against the similarly colored shoreline, but its specific function has not been explained. Dark ventral plumage likely provides camouflage from active fish and crab prey. Dark dorsal plumage likely provides camouflage on the dark shoreline from above. Although the Galapagos lacks predators, four bird species steal prey from herons, suggesting that the dark plumage of Lava Herons may function to provide camouflage against piratical birds. Whereas the complex plumage patterns of most Butorides populations renders those birds cryptic within their usual densely vegetated habitat, dark plumage is similarly cryptic along the exposed dark shoreline of the Galapagos.

Cheek Plumage Uniformity as a Social Status Signal in Great Tits

Some plumage patterns in birds, such as irregularities of feathers, are potential amplifiers because they can reveal damage by conspecifics and therefore social status. We experimentally manipulated the pattern of the white cheeks of male great tits (Parus major) in order to simulate the effects of peckings by others and thus investigate possible changes in dominance during agonistic encounters at artificial feeders exposed to different risks of predation during winter. As predicted, manipulated birds were displaced by controls from safe feeders, and performed a lower number of aggressions and with lower success, although they did not receive more aggressions as expected from the fact that efficient agonistic displays can avoid the occurrence of overt aggressions. Thus, our manipulation changed the social status of birds by converting individuals with manipulated cheeks into subordinates. We propose that cheek colour uniformity acts as an amplifier of the outcomes of aggressions in great tits.

A method to quantify the regularity of barred plumage patterns

Barred plumage is common among bird species. It is often interpreted as a form of crypsis because pigmentation patterns are less detectable against heterogeneous backgrounds. However, it has also been suggested that barred plumage could signal plumage condition, because it makes irregularities in the plumage perceptually salient. Little empirical work exists on the function of barred plumage, in part because we lack a way for quantifying the regularity of the pattern. Here, we present a method to analyze digital photographs of barred plumage and quantify the regularity of its pattern, and also provide software to perform the analysis. Using museum skins of five avian species, we tested under which conditions the method reliably captures differences among conspecific males in the regularity of their barred pattern. We found that measurements of regularity were highly repeatable when lighting conditions were standardized, unlike under variable illumination, and a relatively large area of barred plumage was analyzed, rather than small and non-representative subsections of plumage. The range of conditions under which the method performs well makes it adequate for use in the field, and we hope that it fosters research on the function of barred plumage as a communication signal.

Phylogenetic relationships of flowerpeckers (Aves: Dicaeidae): Novel insights into the evolution of a tropical passerine clade

Understanding the relationships and evolution of flowerpeckers has been challenging, particularly as no phylogenetic study has as yet assessed the group. Here, we present a first such analysis of this clade based on sequences of two mitochondrial genes and one nuclear intron. Our analyses offer strong support for monophyly of the Dicaeidae. Within the family, 4 Dicaeum species (D. chrysorrheum, D. melanoxanthum, D. agile, and D. everetii) had closer affinity to Prionochilus, although tests of alternative topologies could not reject reciprocal monophyly of the two genera. Across the family, overall bill shape trends from more stout bills basally to more slender and medium bills, whereas sexual dichromatism and plumage patterns show much more homoplasy. Taxonomically, generic allocations may need to be changed to reflect historical relationships better.

Hybrid, Subspecies, or Species? The Validity and Taxonomic Status ofPhaethornis longuemareus aethopygaZimmer, 1950 (Trochilidae)

ABSTRACT. Phaethornis longuemareus aethopyga was described by John T. Zimmer in 1950 and treated as a valid subspecies until it was proposed that the three known specimens were hybrids between P. ruber and P. rupurumii amazonicus. On the basis of some recently collected specimens, we reevaluated the validity of P. l. aethopyga. Despite showing some differences related to age and sex, all specimens agree in the general plumage pattern and are fully diagnosable when compared with any other taxon of the genus. The hypothesis of a hybrid origin becomes unsustainable when one notes that (1) P. l. aethopyga has characters that are unique and absent in the purported parental species, such as the white outer margins at the base of the rectrices; and (2) P. l. aethopyga occurs far from the distribution of one of the alleged parental species. Furthermore, field data show that P. l. aethopyga has attributes typical of a valid and independent taxon, such as lekking behavior. Therefore, given its overall diagnosis, P....

Geographic Variation in Plumage Pattern and Coloration of Savannah Sparrows

Abstract We used principal coordinates analysis to analyze variation in 11 plumage characteristics of 1,722 Savannah Sparrows (Passerculus sandwichensis) breeding at 55 different sites from throughout the species' range in Canada, Mexico, and the United States. There is clinal interpopulational variation in size with considerable overlap among localities. Savannah Sparrows resident along the Pacific coast of southern California and Baja California, and those from along the coast of Sinaloa and Sonora (i.e., saltmarsh Savannah Sparrows) differ from those throughout the rest of their range (i.e., non-saltmarsh). Variation among populations of non-saltmarsh Savannah Sparrows was clinal with the exception of those from Sable Island, Nova Scotia, which are consistently more pallid than birds from the adjacent mainland. Western Savannah Sparrows are more pallid than those in the east. The median crown stripe of eastern Savannah Sparrows is distinct, whereas the median crown stripe of western Savannah Sparrows g...

Inferring the phylogeography and evolutionary history of the splendid fairy‐wren Malurus splendens from mitochondrial DNA and spectrophotometry

The phylogeographic structure of the widely distributed arid and semi‐arid Australian splendid fairy‐wren Malurus splendens was investigated by using variation in plumage characters and mitochondrial DNA (mtDNA). We examined sequences of the mtDNA ND2 gene and used spectrophotometry to quantify chromatic variation in plumage in order to test the current morphology‐based intraspecific taxonomy of M. splendens and to discriminate between hypotheses invoking allopatric and parapatric processes in the origin of diversity in the complex. Genetic diversity of M. splendens fell into three divergent geographically structured clades. One represents populations ascribed to the western subspecies M. s. splendens, the other populations of central M. s. musgravi and the third all eastern populations currently ascribed to M. s. emmottorum and M. s. melanotus. Plumage patterns clearly differentiate M. s. splendens and M. s. musgravi, and spectrophotometry identified a step‐wise transition in spectra between M. s. melanotus and M. s. emmottorum. Congruence of patterns of phenotypic and genetic variation among western, central and eastern populations of M. splendens strongly suggests that these populations have diverged in allopatry on either side of historical biogeographic barriers in this region. Decoupled patterns of phenotypic and genetic diversity suggest that the divergence of M. s. melanotus and M. s. emmottorum may have occurred without periods of isolation perhaps in response to differences in local environmental conditions, or alternatively, mtDNA and plumage may have different rates of evolution. Critically, we encountered issues with the placement of the root of the M. splendens complex. The root was placed within the subspecies M. s. splendens separating its northern and southern populations and rendering the subspecies paraphyletic.

112. DIFFERENTIAL DEVELOPMENT OF SEX-RELATED CHARACTERS OF THE GSP AND PNP/DO CHICKENS AFTER LEFT-OVARIECTOMY

To elucidate the strain difference in the sex reversal of genetic female to phenotypic male, GSP and PNP/DO females were left ovariectomized (ovx) between one day to three days after hatching and the degree of masculinization based on sex-related characters, histological analysis of the right gonad and hormone assay were assessed at one year of age. The GSP and PNP/DO inbred lines were both derived from the Fayoumi breed and are only differentiated based on red blood cell antigens type carried by each of the inbred line. Comb and wattles were found to be significantly bigger (P &lt; 0.05) in the GSP ovx compared to the PNP/DO ovx, although male plumage pattern were more pronounced in the PNP/DO ovx. Spurs were observed both in the GSP and PNP/DO ovx with no significant difference (P &gt; 0.05) in length to the respective male controls and body weight were not significantly different (P &gt; 0.05) to the female controls. The size of the right gonad were significantly bigger (P &lt; 0.05) in the GSP ovx than the PNP/DO ovx. Positive correlations were found in the sex related characters as well as plasma testosterone level and the right gonad weight both in the GSP and PNP/DO ovx except for the spur length which resulted into a negative correlation in the PNP/DO ovx. Histological analysis revealed that the right gonad of PNP/DO ovx are morphologically developed compared to GSP ovx showing more advance stages of spermatogenesis. It could be inferred that PNP/DO females which exhibit hereditary persistent right oviduct, are more responsive to the masculinizing effect of ovariectomy compared to GSP females, suggesting that genetic background may have a possible contribution on the degree of masculinization and subsequent development of sex related characters.

Subspeciation in the Short-tailed Grasswren (Amytornis merrotsyi, Maluridae)

The Short-tailed Grasswren (Amytornis merrotsyi) is restricted to the stony spinifex (Triodia) hills of the Gawler Ranges and Flinders Ranges of South Australia. Comparisons of DNA sequences of the mitochondrial ND3 gene reveal an average of 2.1% (1.7–2.3%) sequence divergence between the two isolated populations. Genetic differentiation within populations was less, ranging from 0 to 0.6% between individuals. This pattern of genetic differentiation is comparable to that observed between other recognised subspecies of Amytornis for the same DNA locus. Detailed comparisons of morphology and plumage patterns reveal consistent and diagnosable differences between the two populations confirming earlier more limited morphological assessments. Based on the combination of molecular and morphological differences, the Gawler Ranges population is here named as a separate subspecies, A. m. pedleri subsp. nov.

PARALLEL EVOLUTION OF PLUMAGE PATTERN AND COLORATION IN BIRDS: IMPLICATIONS FOR DEFINING AVIAN MORPHOSPACE

Abstract I studied the recurrence of similar plumage-pattern elements in distantly related taxa across class Aves and examined whether such pattern elements are associated with morphological features, such as body size and anterior emphasis, and with habitat type and age class in selected examples. The identification of recurrent plumage-pattern elements across a wide array of taxa can be interpreted as evidence for parallel evolution and thus for shared developmental pathways. Developmental constraint, therefore, may serve to both generate and delimit the diversity of avian plumage patterns, which are subsequently presented to selection. By examining over 8300 examples of avian plumages mostly from the literature, I derived a plumage-pattern trajectory that can be used as a theoretical model to identify associated morphological trends within various taxonomic contexts of comparison. When comparing species within a clade, as body size increases, plumage pattern often shifts along a trajectory, from counte...

Phylogeographic patterns of differentiation in the Acorn Woodpecker

Abstract Acorn Woodpecker (Melanerpes formicivorus) populations were sampled to evaluate geographic patterns of differentiation and connectivity across the species' range. We observed patterns of differentiation generally coincident with geographic patterns in plumage patterns with distinct subpopulations in Baja California Sur, northern Central America, southern Central America, and mainland Mexico north into the southwestern United States. We confirmed the existence of geographic genetic structuring of populations of this species, although shared haplotypes between Baja California Sur and mainland Mexico suggest that lineage sorting is not yet complete. The process of geographic differentiation and speciation is likely still underway in this group.

DNA evidence shows vocalizations to be a better indicator of taxonomic limits than plumage patterns in Zimmerius tyrant-flycatchers

We investigated mitochondrial and nuclear DNA in the small tyrant-flycatcher genus Zimmerius (Tyrannidae) and show that molecular data are in strong disagreement with morphology-based taxonomy, but in good concordance with vocal characters. Our molecular data identified two independent cases of well-supported polyphyletic species arrangements within this genus that indicate the following taxonomic changes: elevation of Z. acer and Z. albigularis to species level, separation of northern populations of Z. chrysops as a species and inclusion of southern populations of Z. chrysops into Z. viridiflavus. Although polyphyly has rarely been encountered in bird systematics it has previously been shown for two other tyrannid genera and suggests that tyrannid taxonomy may be poorly resolved, presumably as a consequence of the conserved plumage patterns observed in many tyrannid genera. Our study suggests that vocalizations can be a better indicator of taxonomic limits than plumage pattern in tyrannids.

Under Strict Control

EVOLUTION In many species of animals, males and females are strikingly (and visibly) different. Three evolutionary genetic pathways can produce such sexual dimorphism. From the outset, the expression of the alleles for dimorphic traits could be limited to one sex. Or the alleles could be expressed initially in both sexes but subsequently promoted only in one sex or repressed only in the other. Darwin believed that the bright colors and ornaments of males were male-limited from their first appearance, whereas Fisher held that they had been lost from females through the accumulation of suppressors. Coyne et al. weigh these alternatives by examining female hybrids between bird species [such as Costa's (left) and black-chinned (right) hummingbirds] whose males show distinct ornamental traits (for example, plumage patterns and the presence or absence of elongated feathers). Unless the suppressors are completely dominant, these females should show some expression of the male traits. In none of the 13 hybrid cases (from four orders and eight families) that met their search criteria did the females express a male-limited trait. This suggests that male ornaments were sex-limited at their first appearance (perhaps by hormonal or physiological differences between the sexes) or are now controlled by completely dominant modifier alleles or regulatory elements. — SJS Evolution 62 , 214 (2008).

2007 American Society of Naturalists Awards

2007 American Society of Naturalists Awards

Phylogeography of the Buarremon brush-finch complex (Aves, Emberizidae) in Mesoamerica

The Buarremon brush-finches represent a complex suite of populations distributed in the montane New World Tropics from Mexico south to South America. Traditional taxonomic arrangements have separated populations of this genus into three species, based on plumage variation, although plumage patterns are well known to exhibit homoplasy. We present a first detailed phylogeographic and phylogenetic study, focused on Mesoamerican populations, and signal the existence of strong differentiation among populations with a clear geographic structure. We find well differentiated clades for (1) the Sierra Madre Oriental and Sierra Madre del Sur in Oaxaca, (2) western Mexican populations, including the B. brunneinucha populations in the Sierra Madre del Sur and B. virenticeps, (3) Sierra Madre Oriental and Sierra de los Tuxtlas, (4) northern Central America, (5) southern Central America, (6) middle Central America, and (7) South America. We demonstrate a lack of concordance with plumage patterns, and argue for several additional species to be recognized in the complex.

Plumage based classification of the bowerbird genus Sericulus evaluated using a multi-gene, multi-genome analysis

Past classifications of taxa within the bowerbird genus Sericulus (family: Ptilonorhynchidae) conflict since the discovery of hybrids identified though male plumage characteristics. We use molecular data to help define species within this genus, and by estimating a phylogeny, test for lability in the evolution of male plumage patterns. Because this genus includes the most brightly colored bowerbird species, and is hypothesized to be the basal genus of the avenue building bowerbird clade, the organization of the four taxa within this genus is especially important in understanding how bowerbird plumage coloration evolved. Analyses of two mitochondrial and six nuclear gene regions confirm the basal placement of Sericulus in the avenue building bowerbirds and Sericulus monophyly, and suggests the Australian S. chrysocephalus is the basal Sericulus species. Our analysis additionally supports the existence of three New Guinea Sericulus species, contrary to some previous plumage based classifications, as they are genetically equidistant from each other. Molecular and geographic data of New Guinea are consistent suggesting a series of speciation events starting approximately 3.7–4.3 MYA leading to four extant Sericulus species. The absence of resolution within the New Guinea species precludes any statements of trait lability, but does suggest that traits under high selection pressures may not accurately indicate species level distinctions within this genus.

ON THE ECOLOGICAL BASIS OF INTERSPECIFIC HOMOPLASY IN CAROTENOID-BEARING SIGNALS

Evidence that similar color patterns occur in unrelated animals with different habits undermines the traditional view that homoplasy evolves through shared ecological selection pressures. Carotenoid pigments responsible for many yellow to red signals exhibit two related properties that could link ecology with appearance by nontraditional means. Ecologic homoplasy could arise through ecophenotypy because all animals must obtain carotenoids through their diet. Such homoplasy also could be hidden from view because increased carotenoid levels are more strongly encoded by decreased reflectance over ultraviolet (UV) wavelengths invisible to humans. To explore these possibilities, I examined apparent matches or mismatches between color and ecology among insectivorous (low carotenoid diet) and frugivorous (high carotenoid diet) bird species in relation to the typical yellow and black plumage pattern of insectivorous, UV-sensitive titmice (Paridae). Diagnostic features of reflectance spectra indicated that all yellow plumages resulted from carotenoids, black plumages from melanins, and olive green plumages from codeposition of both pigments. However, reflectance by carotenoid-bearing plumages correlated with diet independent of plumage pattern; compared to the insectivores, frugivores had reduced amounts of UV reflectance, and to a lesser extent, "red shifts" in longer-wavelength reflectance. Furthermore, an asymptotic decrease in amount of UV with increased redness implied that plumage reflectance of insectivorous species differed more over UV wavelengths, whereas that of frugivorous species differed more over longer wavelengths. I verified that dietary links to plumage reflectance resulted from greater amounts of plumage carotenoids in frugivores, presumably due to their carotenoid-rich diets. All of these ecological associations transcended post-mortem or post-breeding color change, and phylogeny. Thus, predictable associations between avian-visible plumage reflectance, pigmentation, and diet across evolutionary scales may arise directly (diet per se) or indirectly (honest signaling of diet) by ecophenotypy, although various genetic factors also may play a role.