The island rule and its application to multiple plant traits

<p>The Island Rule refers to a continuum of body size changes where large mainland species evolve to become smaller and small species evolve to become larger on islands. Previous work focuses almost solely on animals, with virtually no previous tests of its predictions on plants. I tested for (1) reduced floral size diversity on islands, a logical corollary of the island rule and (2) evidence of the Island Rule in plant stature, leaf size and petiole length. Endemic island plants originated from small islands surrounding New Zealand; Antipodes, Auckland, Bounty, Campbell, Chatham, Kermadec, Lord Howe, Macquarie, Norfolk, Snares, Stewart and the Three Kings. I compared the morphology of 65 island endemics and their closest ‘mainland’ relative. Species pairs were identified. Differences between archipelagos located at various latitudes were also assessed. Floral sizes were reduced on islands relative to the ‘mainland’, consistent with predictions of the Island Rule. Plant stature, leaf size and petiole length conformed to the Island Rule, with smaller plants increasing in size, and larger plants decreasing in size. Results indicate that the conceptual umbrella of the Island Rule can be expanded to plants, accelerating understanding of how plant traits evolve on isolated islands.</p>

The island rule and its application to multiple plant traits

<p>The Island Rule refers to a continuum of body size changes where large mainland species evolve to become smaller and small species evolve to become larger on islands. Previous work focuses almost solely on animals, with virtually no previous tests of its predictions on plants. I tested for (1) reduced floral size diversity on islands, a logical corollary of the island rule and (2) evidence of the Island Rule in plant stature, leaf size and petiole length. Endemic island plants originated from small islands surrounding New Zealand; Antipodes, Auckland, Bounty, Campbell, Chatham, Kermadec, Lord Howe, Macquarie, Norfolk, Snares, Stewart and the Three Kings. I compared the morphology of 65 island endemics and their closest ‘mainland’ relative. Species pairs were identified. Differences between archipelagos located at various latitudes were also assessed. Floral sizes were reduced on islands relative to the ‘mainland’, consistent with predictions of the Island Rule. Plant stature, leaf size and petiole length conformed to the Island Rule, with smaller plants increasing in size, and larger plants decreasing in size. Results indicate that the conceptual umbrella of the Island Rule can be expanded to plants, accelerating understanding of how plant traits evolve on isolated islands.</p>

Significant progressive heterobeltiosis in banana crossbreeding

Background Heterobeltiosis is the phenomenon when the hybrid’s performance is superior to its best performing parent. Banana (Musa spp. AAA) breeding is a tedious, time-consuming process, taking up to two decades to develop a consumer acceptable hybrid. Exploiting heterobeltiosis in banana breeding will help to select breeding material with high complementarity, thus increasing banana breeding efficiency. The aim of this study was therefore to determine and document the level of heterobeltiosis of bunch weight and plant stature in the East African highland bananas, in order to identify potential parents that can be used to produce offspring with desired bunch weight and stature after a few crosses. Results This research found significant progressive heterobeltiosis in cross-bred ‘Matooke’ (highland cooking) banana hybrids, also known as NARITAs, when grown together across years with their parents and grandparents in Uganda. Most (all except 4) NARITAs exhibited positive heterobeltiosis for bunch weight, whereas slightly more than half of them had negative heterobeltiosis for stature. The secondary triploid NARITA 17 had the highest heterobeltiosis for bunch weight: 249% versus its ‘Matooke’ grandparent and 136% against its primary tetraploid parent. Broad sense heritability (across three cropping cycles) for yield potential and bunch weight were high (0.84 and 0.76 respectively), while that of plant stature was very low (0.0035). There was a positive significant correlation (P < 0.05) between grandparent heterobeltiosis for bunch weight and genetic distance between parents (r = 0.39, P = 0.036), bunch weight (r = 0.7, P < 0.001), plant stature (r = 0.38, P = 0.033) and yield potential (r = 0.59, P < 0.001). Grandparent heterobeltiosis for plant stature was significantly, but negatively, correlated to the genetic distance between parents (r = − 0.6, P < 0.001). Conclusions Such significant heterobeltiosis exhibited for bunch weight is to our knowledge the largest among main food crops. Since bananas are vegetatively propagated, the effect of heterobeltiosis is easily fixed in the hybrids and will not be lost over time after the release and further commercialization of these hybrids.

Significant progressive heterobeltiosis in banana crossbreeding

Background: Heterobeltiosis is the phenomenon when the hybrid’s performance is superior to its best performing parent. Banana ( Musa spp. AAA) breeding is a tedious, time-consuming process, taking up to two decades to develop a consumer acceptable hybrid. Exploiting heterobeltiosis in banana breeding will help to select breeding material with high complementarity, thus increasing banana breeding efficiency. The aim of this study was therefore to determine and document the level of heterobeltiosis of bunch weight and plant stature in the East African highland bananas, in order to identify potential parents that can be used to produce offspring with desired bunch weight and stature after a few crosses.Results: This research found significant progressive heterobeltiosis in cross-bred ‘Matooke’ (highland cooking) banana hybrids, also known as NARITAs, when grown together across years with their parents and grandparents in Uganda. Most (all except 4) NARITAs exhibited positive heterobeltiosis for bunch weight, whereas slightly more than half of them had negative heterobeltiosis for stature. The secondary triploid NARITA 17 had the highest heterobeltiosis for bunch weight: 249% versus its matooke grandparent and 136% against its primary tetraploid parent. Broad sense heritability (across three cropping cycles) for yield potential and bunch weight were high (0.84 and 0.76 respectively), while that of plant stature was very low (0.0035). There was a positive significant correlation ( P < 0.05) between grandparent heterobeltiosis for bunch weight and genetic distance between parents (r = 0.39, P = 0.036), bunch weight (r = 0.7, P < 0.001), plant stature (r = 0.38, P = 0.033) and yield potential (r = 0.59, P < 0.001). Grandparent heterobeltiosis for plant stature was significantly, but negatively, correlated to the genetic distance between parents (r = -0.6, P < 0.001).Conclusions: Such significant heterobeltiosis exhibited for bunch weight is to our knowledge the largest among main food crops. Since bananas are vegetatively propagated, the effect of heterobeltiosis is easily fixed in the hybrids and will not be lost over time after the release and further commercialization of these hybrids.

Significant Progressive Heterobeltiosis in Banana Crossbreeding

Background: Heterobeltiosis is the phenomenon when the hybrid’s performance is superior to its best performing parent. Banana ( Musa spp. AAA) breeding is a tedious, time-consuming process, taking up to two decades to develop a consumer acceptable hybrid. Exploiting heterobeltiosis in banana breeding will contribute to selecting breeding material with high compatibility, thus increasing banana breeding efficiency. The aim of this study was therefore to determine and document the level of heterobeltiosis of bunch weight and plant stature in the East African highland bananas, in order to identify potential parents that can be used to produce offspring with desired bunch weight and stature after a few crosses. Results: This study found significant progressive heterobeltiosis in cross-bred ‘Matooke’ banana hybrids, also known as NARITAs, when grown together across years with their parents and grandparents in Uganda. All NARITAs exhibited positive heterobeltiosis for bunch weight, whereas half of them had negative heterobeltiosis for stature. NARITA 17 had the highest heterobeltiosis for bunch weight (248.7%), followed by 26666S-1 (229.3%), while the lowest was noted in NARITA 19 (1.2%). Heritability for yield potential and bunch weight were high (0.84 and 0.76 respectively), while that of plant stature was very low (0.0035). There was a positive significant correlation ( P < 0.05) between grandparent heterobeltiosis for bunch weight and genetic distance between NARITAs’ parents (r = 0.39, P = 0.036), bunch weight (r = 0.7, P < 0.001), plant stature (r = 0.38, P = 0.033) and yield potential (r = 0.59, P = 0.0004). Grandparent heterobeltiosis for plant stature was significantly, but negatively, correlated to the genetic distance between NARITA parents (r = -0.6, P = 0.0004). Conclusions: Such significant heterobeltiosis exhibited for bunch weight is to our knowledge the largest among main food crops. Since bananas are vegetatively propagated, the effect of heterobeltiosis is easily fixed in the hybrids and will not be lost over time after the release and further commercialization of these hybrids.

Plants obey (and disobey) the island rule

The island rule predicts that small animals evolve to become larger on islands, while large animals evolve to become smaller. It has been studied for over half a century, and its validity is fiercely debated. Here, we provide a perspective on the debate by conducting a test of the island rule in plants. Results from an extensive dataset on islands in the southwest Pacific illustrate that plant stature and leaf area obey the island rule, but seed size does not. Our results indicate that the island rule may be more pervasive than previously thought and that support for its predictions varies among functional traits.