News Category
アーカイブ | RSS |
 投稿日時: 2022-01-19 10:39:54 (134 ヒット)



日時:2月17日(木) 13:30-14:30 




Evolutionary ecology of sexual reproduction: sexual selection, reproductive interference, and community structure


Daisuke Kyogoku (The Museum of Nature and Human Activities)


In sexually reproducing organisms, mating with individuals of the opposite sex is necessary to produce offspring. Mating process raises competition for mating opportunities among same-sex individuals (i.e. sexual selection) and the conflict of evolutionary interest between the sexes (sexual conflict), which drive the evolution of reproductive traits. Because reproductive traits can mediate interspecific interactions (e.g. reproductive interference), reproductive trait evolution can eventually influence the community structure. In this talk, I present three different studies that are related to the evolutionary ecology of sexual reproduction, and by doing so I discuss ways in which sexual reproduction is relevant to the origin and/or maintenance of biodiversity. First, I show a likely case of sexual conflict in a sexually reproducing dandelion, where the timing of flower closure is influenced by the identity of the pollen deposited on the stigma. Second, I present a case study of how reproductive trait evolution due to within-species sexual selection can mediate the strength of reproductive interference in a pair of seed beetle species. Third, I present a simulation model of secondary contact with genetically incompatible hybridization. This model suggests that habitat segregation can evolve without tradeoff in resource use ability and that habitat segregation is more likely to be found in nature than species recognition divergence, which has historically been more appreciated than habitat segregation in this context. I will also briefly present some of my ongoing projects and discuss future research plans.






有性生殖をする生物では、子孫を残すために異性個体との配偶が必要である。繁殖プロセスは、同性個体(特にオス)間の繁殖機会をめぐる競争(i.e. 性選択)やオスとメスの利害対立(性的対立)を生み出すことで、繁殖形質の進化を駆動する。またこうして進化した繁殖形質は繁殖干渉などの種間相互作用を介在するため、群集構造にも影響を与えると期待される。本発表ではこうした有性生殖にまつわる進化生態学的な話題を3つ提供し、全体として有性生殖が多様性の創出と維持にどのように関わっているのかを議論する。まず有性タンポポを例にオスとメスの利害対立の例と考えられる事例(花を閉じる時刻が受け入れた花粉の性質に影響される)を紹介する。続いて、種内の性選択により進化した繁殖形質がいかに繁殖干渉の強さに影響するかを昆虫のマメゾウムシ類で検証した例を紹介する。最後に、繁殖干渉によって資源利用能力のトレードオフ無しに棲み分けが進化しうること(さらには、棲み分けのほうが従来重視されてきた種認識の分化よりも進化しやすいと考えられること)を示した数理モデル研究を紹介する。発表では現在行っている研究についても簡単に紹介し、将来の展望についても議論したい。



 投稿日時: 2019-10-29 09:05:05 (2193 ヒット)


  • 日時:2019年12月3日(木)15:00-16:30
  • 場所:地球環境科学研究院 D201

講演題目1「ハエの翅の模様が作られる仕組み 」

15:00-15:45 越川 滋行(生物圏科学専攻、生態遺伝学コース)

ミズタマショウジョウバエの翅 (撮影 越川滋行)



15:45-16:30 相場 慎一郎 (生物圏科学専攻、多様性生物学コース)

ボルネオ島のキナバル山 (撮影 相場慎一郎)


連絡先:北海道大学大学院地球環境科学研究院 生態遺伝学分野 越川滋行

 投稿日時: 2019-07-12 14:57:30 (1955 ヒット)

The Environmental Earth Science Seminar will be held as follows.

Location: D101 in GSES
Date and Time: 16:30-18:00 on July 18th (Thu)
Speaker: Marc Abrams (Department of Ecosystem Science and Management Penn State University)

Title: The impact of global change on tree species growth and dominance in the eastern U.S.

Abstract: Global change processes, including climate and natural and anthropogenic (land-use) disturbances have profoundly impacted tree dominance and growth rates worldwide.  To help decipher the relative importance of various drivers of forest change tree species/genera were partitioned into temperature, shade tolerance, and pyrogenicity classes and applied to comparative tree-census data.  We examined changes during the Euro-American period (ca. 1500 to present), which spans two major climatic periods, from Little Ice Age and the Anthropocene. We found that most tree species and age classes exhibited increasing basal area increment (BAI) and/or ring width index (RWI) in recent years.  This is particularly unusual for trees in the older age classes that we expected to have declining growth in the latter years, as predicted by physiological growth models.  There exists an inverse relationship between growth rate and increasing age class.  The oldest trees within each species have consistently slow growth throughout their lives, implying an inverse relationship between growth rate and longevity. Younger trees (< 60 years of age) within each species are consistently growing faster than the older trees when they were the same age resulting from a higher proportion of fast-growing trees in these young age classes. In contrast, changes in tree dominance were not highly consistent with warming. Instead, post-European settlement disturbance regimes mostly overrode climate signals across the eastern US. In the north, intensive and expansive disturbances resulted in the ubiquitous loss of conifers and a large increase in Acer, Populus, and Quercus in northern hardwoods, whereas to the south, these disturbances perpetuated the dominance of Quercus. Mid-twentieth century fire suppression led to large increases in Acer in the latter case, often leading to significant warm-to-cool shifts in temperature class. These series of studies helped elucidate the wide spread and profound impacts of global change on trees and delivered some unexpected results. The reasons for increasing tree growth in the study region and the main drivers of forest change will be discussed, including the climate-disturbance debate.

If you have any question regarding this seminar, please feel free to contact Shiro Tsuyuzaki (

Thank you for reading.
See you in D101 by 16:30 on July 18th (Thu).


Graduate School of Environmental Sceince, Hokkaido University