Pollinator-driven selection is thought to drive much of the extraordinary diversity of flowering plants. Plants that produce floral traits preferred by particular pollinators are more likely to receive conspecific pollen and to evolve further adaptations to those pollinators that enhance pollination and ultimately generate floral diversity. Two mechanisms in particular, sensory bias and learning, are thought to explain how pollinator preference can contribute to divergence and speciation in flowering plants. While the preferences of pollinators, such as bees, flies, and birds, are frequently implicated in patterns of floral trait evolution, the role of learning in generating reproductive isolation and trait divergence for different floral types within plant populations is not well understood. Floral color polymorphism in particular provides an excellent opportunity to examine how pollinator behavior and learning might maintain the different floral morphs. In this study we asked if bumble bees showed innate preferences for different color morphs of the pollen-only plant Solanum tridynamum, whether bees formed preferences for the morphs with which they had experience collecting pollen from, and the strength of those learned preferences. Using an absolute conditioning protocol, we gave bees experience collecting pollen from a color polymorphic plant species that offered only pollen rewards. Despite initially-naïve bees showing no apparent innate bias toward human-white versus human-purple flower morphs, we did find evidence of a bias in learning. Specifically, bees learned strong preferences for purple corollas, but learned only weak preferences for hypochromic (human-white) corollas. We discuss how our results might explain patterns of floral display evolution, particularly as they relate to color polymorphisms. Additionally, we propose that the ease with which floral visual traits are learned—i.e., biases in learning—can influence the evolution of floral color as a signal to pollinators.

Males of the Mexican lizard Sceloporus minor (Phrynosomatidae) exhibit striking variation in dorsal coloration, both within and among populations, which may have arisen by sexual selection. The possible significance of this trait was investigated through a combination of observational and experimental approaches. This research revealed that males in one population (La Manzana) in NW Hidalgo exhibit three discrete color morphs (blue, yellow, red) each characterized by morphological, physiological and behavioral differences. Furthermore, these morphs can be identified by an objective approach to color assessment (spectroradiometry). In addition, males in a second population (Escalerillas) from SE San Luis Potosí were also found to occur in at least two color morphs (yellow and red), suggesting that color polymorphism may be general in this species. The hypothesis of sensory exploitation by male contest competition was tested for S. minor from Escalerillas; however, no support for this hypothesis was found. Overall, results from this study are consistent with the hypothesis of alternative reproductive tactics in S. minor.

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第21875号 / 人博第904号 / 新制||人||215(附属図書館) / 2018||人博||904(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 瀬戸口 浩彰, 教授 加藤 眞, 教授 市岡 孝朗, 准教授 西川 完途 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DGAM

No description available.

<p>Diversity in coloration is a common phenomenon in marine invertebrates, although the ecological significance of the diversity is often unknown. Patterns of geographic variability, particularly with respect to color phenotypes, are evident in many organisms and may provide visual evidence of natural selection. </p><p>This dissertation examined the geographic and genetic variability of color patterns and morphology of the sea urchin <italic>Lytechinus variegatus </italic>. This study had 3 objectives: 1) to describe and quantify phenotypic diversity--color and morphology--throughout the geographic range; 2) to determine the heritability of color in genetic crosses between individuals with similar and differing phenotype; 3) to assess the degree of genetic divergence between and within the regions and congruence between the phylogenetic mitochondrial COI data and color phenotypes seen in the field.</p><p>The distribution of color phenotypes in the field is highly variable across the geographic range which stretches from Beaufort NC to southern Brazil and throughout the Gulf of Mexico and Caribbean. Urchins in each of the 5 regions sampled (Beaufort, Gulf, Keys, Panama and Brazil) have a distinct phenotypic composition despite the presence of similar color morphs. The two regions at the extremes--Beaufort and Brazil--demonstrate the most homogeneous phenotypes, each with a single dominant color morph. The Keys has the most heterogeneous composition with all 14 color morphs present. Morphological diversity mirrors color diversity in being highly variable across the range. Urchins in Beaufort are significantly different morphologically from urchins in the central portion of the range, with thicker, flatter tests and longer more robust spines.</p><p>The heritability of color phenotypes and morphology suggests that genes rather than environment have a major role in color phenotype and patterning as well as morphology in test, spines and lanterns. F₁ and F₂ offspring of Beaufort and Tavernier Key crosses resemble the parental phenotypes in both morphology and color phenotype. Hybrids from crosses between regions have a mixed color palette and intermediate morphological characteristics. The crosses establish that in <italic>L. variegatus </italic>the white phenotype is a dominant autosomal trait and green and purple are recessive and co-expressed. Patterning of the test and spines is dominant to non-patterning. </p><p>Analysis of the mitochondrial COI gene in urchins from Beaufort, Gulf and Keys regions revealed two clades. Clade 1 composed exclusively of Keys urchins differed significantly (F_ST = 0.89, <italic>P</italic> < 0.001) from Clade 2 composed of urchins from Beaufort, Gulf and Keys. Genetic differentiation within Clade 2 was zero, indicating that urchins in these regions are genetically identical. The genetic split between phenotypically indistinguishable Keys urchins suggests cryptic species. Genetic differentiation does not concord with phenotypic and morphological differentiation. No structure was detected with regards to color phenotype in either clade or region of origin in Clade 2.</p> / Dissertation

No description available.

Life history traits affect the timing and pattern of maturation, reproduction, and survival during an organism’s lifecycle and are the major components influencing Darwinian fitness. Co-evolved patterns of these traits are known as life history strategies (LHS) and variation occurs between individuals, populations, and species. The polymorphisms underlying LHS are important targets of natural selection, yet the underlying genes and physiological mechanisms remain largely unknown. Mapping the genetic basis of a LHS and subsequently unraveling the associated physiological mechanisms is a challenging task, as complex phenotypes are often polygenic. However, in several systems discrete LHS are maintained within the population and are inherited as a single locus with pleiotropic effects. These systems provide a promising starting point for investigation into LHS mechanisms and this thesis focuses on one such strategy - the Alba polymorphism in Colias butterflies. Alba is inherited as a single autosomal locus, expressed only in females, and simultaneously affects development rate, reproductive potential, and wing color. Alba females are white, while the alternative morph is yellow/orange. About 28 of 90 species exhibit polymorphic females, though whether the Alba mechanism and associated tradeoffs are conserved across the genus remains to be determined. In this thesis I primarily focus on the species Colias croceus and integrate results from lipidomics, transcriptomics, microscopy, and genomics to gain insights to the proximate mechanisms underlying Alba and Alba’s evolution within the genus. Lipidomics confirm that, consistent with findings in New World species, C. croceus Alba females have larger abdominal lipid stores than orange, an advantage which is temperature dependent and arises primarily due to mobilized lipids. Gene expression data suggests differences in resource allocation, with Alba females investing in reproduction rather than wing color, consistent with previous findings in other Colias species. Additionally, I identify a morphological basis for Alba’s white wing color. Alba females from C. croceus, an Old World species, and Colias eurytheme, a New World species both exhibit a significant reduction in pigment granules, the structures within the wing scale that contain pigment. This is a trait that seems to be unique to Colias as other white Pierid butterflies have an abundance of pigment granules, similar to orange females. I also map the genetic basis of Alba to a single genomic region containing an Alba specific, Jockey-like transposable element insertion. Interestingly this transposable element​ is located downstream of BarH-1, a gene known to affect pigment granule formation in Drosophila. Finally, I construct a phylogeny using a global distribution of 20 Colias species to facilitate investigations of Alba’s evolution within the genus. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>