The evolution and development of leaves in land plants has been of great debate among botanists for decades (Gifford and Foster 1989). Questions about the origin of microphylls and megaphylls as well as the homology of all megaphylls remain unanswered (Gifford and Foster 1989; Kenrick and Crane 1997). Molecular genetic studies are beginning to provide additional data to assess the homology of leaves, and such studies have elucidated aspects of leaf development in the flowering plants and given insight into microphyll development in lycophytes; however, comparable data is largely lacking for ferns (Tomescu 2009).<\/p>\n
Most members of the family Dryopteridaceae, the family in which Elaphoglossum<\/i> is placed, such as Dryopteris<\/i>, Megalastrum<\/i>, Mickelia<\/i>, and Bolbitis<\/i> are characterized by divided leaves (Hennipman 1977; Tryon and Tryon 1982). The molecular phylogenetic analyses have recovered Mickelia<\/i> as the sister genus of Elaphoglossum<\/i>(Moran et al. 2011). These phylogenetic hypotheses suggest that the simple, entire leaves typical of Elaphoglossum<\/i>represent a derived state among dryopteroid ferns.<\/p>\n
There are at least five species in the genus Elaphoglossum<\/i> that have dissected leaves. Morphological (Mickel 1980) and molecular phylogenetic studies (Rouhan et al. 2004) have shown that the dissected leaf species of Elaphoglossum<\/i> (1) belong to the genusElaphoglossum<\/i> and do not merit distinction as separate genera, and (2) are not monophyletic. Three of the Elaphoglossum<\/i> species with dissected leaves belong toElaphoglossum<\/i> section Squamipedia<\/a>. Based on the molecular phylogenetic hypothesis it seems to be that the dissected leaves of these three species might represent a reversion to the divided condition. Thus, by using Elaphoglossum<\/i> section Squamipedia<\/a> and its sister genus Mickelia<\/i> (with divided-leaves), the following sequence of leaf evolution can be analyzed:<\/p>\n divided leaves (Mickelia<\/i>) \u2192 simple, entire leaves (Elaphoglossum) \u2192 divided leaves (three species of sect. Squamipedia).<\/b><\/p>\n From the developmental point of view the apparent three independent reversions to dissected leaves in Elaphoglossum<\/i> section Squamipedia<\/a> suggest a change in only one or a few genes. We are interested in comparing the expression of leaf development genes in these natural variants of leaf shape and in determining whether changes in gene expression correlate with changes in leaf shape. The developmental data that we collect would be analyzed within a phylogenetic framework, and furthermore can be compared to what is known about development and gene expression in the leaves of seed plants and lycophytes, thus contributing a piece to the comparative puzzle about the homology of land plant leaves.<\/p>\n","protected":false},"excerpt":{"rendered":" The evolution and development of leaves in land plants has been of great debate among botanists for decades (Gifford and Foster 1989). Questions about the origin of microphylls and megaphylls as well as the homology of all megaphylls remain unanswered … Continued<\/a><\/p>\n","protected":false},"author":1,"featured_media":45,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"","meta":[],"portfolio-type":[],"_links":{"self":[{"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/portfolio\/44"}],"collection":[{"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/portfolio"}],"about":[{"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/types\/portfolio"}],"author":[{"embeddable":true,"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/comments?post=44"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/media\/45"}],"wp:attachment":[{"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/media?parent=44"}],"wp:term":[{"taxonomy":"portfolio-type","embeddable":true,"href":"https:\/\/sweetgum.nybg.org\/science\/projects\/elaphoglossum\/wp-json\/wp\/v2\/portfolio-type?post=44"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}